( informal )
1.
used when you are thinking of what to say next :
Well, you know, it's difficult to explain.
2.
used to show that what you are referring to is known or understood by the person you are speaking to :
Guess who I've just seen? Maggie! You know—Jim's wife.
You know that restaurant round the corner? It's closed down.
3.
used to emphasize sth that you are saying :
I'm not stupid, you know.