It's a question tag, and it's usually used to ask the other person if they agree, understand or share the other persons point of view. Most people use it because they want to know what the other persons thoughts are, the question tag tends to inquire to the other person what they think, whether they disagree and so on. Eg: A: "I really hate when there's so many ads on TV, you know? B: "Yeah i know what you mean, it's a real pain" Hope this helps!

Hi... It is a bad habit...

It is like: "You share the same opinion with me?" " You agree to what I say?" "Do you realize the fact that I am so and so...?" I use 'you know ' sometimes, you know ?;)

Its a figure of speech that doesn't mean anything in context. Just one of the many odd common speech points of english.

You know, they don't speak good English.