What is the main concept of using lexical,linguistic, semantic or syntactic approach in NLP for cyberbullying I am really in need of some explanation, I am working on an NLP cyber-bullying detection tool which I will deploy to the web using Django framework, however, am stuck on some idea, can someone explain to me...What is the main concept of using lexical, linguistic, semantic or syntactic approach in (NLP) and how is applied in cyber-bullying or what are the step or why does people say I built this cyber-bullying system from a linguistic approach, I know POS-tagging is way of grouping word and look for dependency in other word, my idea of POS-tagging is a synonym of semantic because POS-tagging is a process linking words to it root and representation word in an understandable context correct me if wrong.

I read an article where a paper tackled a project using a predictive analysis approach with feature extraction techniques, Naive Bayes for classification and to train the model, in the discussion they also spoke on how other team used the Semantics approach to classifier cyber-bullying. I know of data cleaning, tokenization stemming and most of feature extraction model, however, am stuck on the problem of approach which is what is the relevant on lexical, semantic or syntactic and how are they been approached.
I suggest to check out some introductory books on NLP, e.g. Natural Language Processing with Python. This is a very accessible and practical introduction and useful even if you won't be working in Python. Another, more detailed text book is Speech and Language Processing by Jurafsky and Martin.

You need to understand the basics first, and these are independent of your particular application (cyber bullying). And I think this is too much knowledge to reasonably fit into a response here. But just to give you an idea:

Lexical: information about the words (meaning and structure)

Syntactic: the structure of the text (how words make up phrases, and how phrases make up sentences, the rules that govern that process)

Semantic: about the meaning of text (as it is constructed from the meaning of the words and their composition).

These are usually part of a pipeline, which means you need start processing from the words, then look how they form sentences, and then you can look at the meaning.

Your understanding of POS-tagging seems off the mark: it is the process of assigning words in a text their part of speech (POS), e.g. verb, noun, adjective etc. As such it is part of the syntactical processing (but requires lexical knowledge too), but is also useful for semantic analysis further down.