What does 尔 really mean?
There are many resources which &quot;decompose characters&quot;, but most of them do not give any insight as to how Chinese characters actually work in relation to the language, and looking at these resources is very counterproductive. The answer accepted here on the character decomposition of 「你」 is from one of the few resources which do give a correct idea of how characters work.
Someone can tell you &quot;what 「尔」 really means&quot; through its decomposition (in this case, decomposition produces only one component, as 「尔」 isn't made up from anything apart from itself),

 商甲前7.36.1合集3298西周金史墻盤集成10175戰國・晉金中山王鼎集成2840篆八部說文解字隸定　今楷　

 「尔」 is a structural abbreviation of 「爾」.

 「爾」 depicts a spiked weapon (similar to what is now written as 刺) adorned with decorative feathers. Some variants of the character left out the adornments, leading to the character 「尔」.
 The meaning you for the character 「尔」 is a phonetic loan (rebus borrowing).

but, before there is an understanding of how Chinese characters work in relation to the language, any kind of character decomposition is not going to help at all, so it pays to understand the relationship between characters and the Chinese language first, before indulging in any kind of character decomposition.

What does a Chinese character represent?
Chinese characters represent morphosyllables: that is, they represent

morphemes, the smallest meaningful units in any language, but whose sound is consistently organised as

syllables.


In colloquial terms, this means a Chinese character simultaneously represents meaning and sound, and the sound is (almost) always one syllable.
It pays to thoroughly understand what a morpheme is, so I'll paste Wikipedia's English examples of morphemes below:

Every morpheme can be classified as either free or bound. Since the categories are mutually exclusive, a given morpheme will belong to exactly one of them.

Free morphemes can function independently as words (e.g. town, dog) and can appear within lexemes (e.g. town hall, doghouse).
Bound morphemes appear only as parts of words, always in conjunction with a root and sometimes with other bound morphemes. For example, un- appears only accompanied by other morphemes to form a word. Most bound morphemes in English are affixes, particularly prefixes and suffixes. Examples of suffixes are -tion, -sion, -tive, -ation, -ible, and -ing.


Please note that morphemes are not, in general words; free morphemes can function as words, while bound morphemes cannot. English is a word-based orthography; the writing is divided by spaces into words. Chinese is a morpheme-based orthography; the writing is composed from characters, with each character representing a morpheme.

How do Chinese characters work?
Each Chinese character is composed of one or more components. Since we know that each Chinese character represents a morphosyllable, that is, a morpheme having simultaneously meaning and a one-syllable sound, then the only things that these one or more components do is throw hints at what the morphosyllable represented by the character is.
How do character components hint at a morphosyllable? For each of the one or more components, they can hint at the morphosyllable in one of several ways. The three major ones are:

The component can hint at the meaning of the morphosyllable
The component can hint at the sound of the morphosyllable
The component can simultaneously hint at the meaning and sound of the morphosyllable.

Components which employ the above morphosyllable hint methods are characters in their own right. However, it is generally not a good idea to further decompose character components into their own constituents; that is, perform recursive decomposition, because these further decomposed components either only peripherally hint at the morphosyllable, or do not hint at the moprhosyllable at all.
Correct and not-so-correct ways of decomposing characters can be shown through an example:

 Worked example: Character decomposition of 「鴻」 (Baxter-Sagart OC: /*[ɡ]ˤoŋ/, Mandarin: hóng, a type of swan)
 「鴻」 is comprised of the following morphosyllable hints:
 
   Morphosyllable hint type 2 - Sound hint: 「江」 (/*kˤroŋ/, Mandarin: jiāng)
   
    The meaning of 「江」, river, is not relevant to morphosyllable represented by 「鴻」.
   
  
   Morphosyllable hint type 1 - Meaning hint: 「鳥」 (bird)
   
    The sound of 「鳥」, /*tˤiwʔ/, Mandarin: niǎo, is not relevant to the morphosyllable represented by 「鴻」.
   
  
 

 

 Even though the character 「鴻」 is written in the following stroke sequence,

 

 presenting the &quot;decomposition&quot; of 「鴻」 as the character's strokes, ㇔㇔㇀㇐㇑㇀㇒㇑㇕㇐㇐㇐㇆㇒㇔㇔㇔, does not tell you anything about the morphosyllable represented by 「鴻」, and asking whether any of these strokes have meaning is not productive.

 Strokes, and the other commonly misunderstood radicals, do not have anything to do with the Chinese language. Chinese characters are not made up of strokes or radicals; they are made up of morphosyllable hints and (almost) nothing else.

In this context, 「尔」 is a character with one component, and good references will not break it down any further. Incorrect decompositions, like the one you've posted in the question*, will suggest very random things that have nothing to do with the meaning or sound of 「尔」, leading people down a time-wasting and misleading journey, and giving a very incorrect idea of what 「尔」 is and how characters work in general. Hopefully, by this stage it is better understood why the following questions and statements are not correct questions to ask and statements to make:
*This particular decomposition comes from the ancient dictionary Shuowen Jiezi.

What does 亅 mean?

「亅」 is a stroke in 「尔」, not a character component of 「尔」 (which only has one component). The meaning of 「亅」, if it has one, is not relevant to 「尔」.


What&#39;s the meaning of the hat like character on top of 尔

「尔」 only has one component, which is itself. It does not contain a hat-like character on top.


The er consist of character dao and xiao.

「尔」 only has one component, which is itself. It is not comprised of 「刀」 and 「小」.


The character xiao consist of number 8 pa with vertical hook.

This decomposition is not correct. 「小」 only has one component (which is itself); it is not comprised of 「八」 and 「亅」. Also, since 「尔」 only has one component (which is itself), it does not contain 「小」; 「小」 has nothing to do with 「尔」.




If the concepts above are understood, then one might start to guess at what a proper description of 「尔」 should or shouldn't look like,

 「尔」 contains one component, which is a morphosyllable hint of type 2: Sound hint (see the top of this answer for the glyph origins and explanation)

, and what role it plays in the character 「你」.

 「你」 is cognate to 「尔」, and they once represented the same word long ago.
 「你」 (Zhengzhang OC: /*nɯʔ/, Mandarin: nǐ, you [second person pronoun]) is comprised of
 
  Morphosyllable hint type 1 - Meaning hint: 「亻」 (person);
  Morphosyllable hint type 3 - Simultaneous sound and meaning hint: 「尔」 (/*njelʔ/, Mandarin: ěr, you).