Why isn't there 1' to 2' direction or something else except 5' to 3' in dna replication?
[Source]

DNA is a polynucleotide. The above structure is of a nucleotide which has three components, a nitrogenous base(yellow), a pentose sugar(purple) and a phosphate group. These nucleotides form phosphodiester linkages to form a polynucleotide.



[Source]

These phosphodiester linkages are formed between 3' and 5' carbons of the pentose sugar which is shown in the above image.



[Source]

The end of DNA having a free phosphate group at 5' of pentose sugar is known as the 5'-end of DNA, and the end of DNA having a free hydroxyl group at 3' of pentose sugar is called the 3'-end of DNA. 

Here, you can play with the DNA.