| | Re: What is "You know" in many sentence?
It can have several meanings :
1. To introduce a topic of conversation : You know that shop on the corner of Oaktree Road? Well, apparently it's closing down.
2. As a hesitation device to give the speaker time to think about what s/he wants to say : I was well, you know, a bit surprised because he was, you know, not the person I'd expected to see. This can be very annoying if the person uses it too often - I once saw an interview with Prince William where he seemed to it every five or six words. like is often used in the same way - He was, like, not the person I expected to see.
3. With rising intonation, a way of checking that someone has been listening an following what you've said : I was surprised, because he was not the person I expected to see. You know?
4. To suggest complicity and shared information between speaker and listener : Well, you know what he's like.
Notice that in 1 and 3 it's actually a question, but question form (Do you know...?) is not used. This is because the speaker assumes that the listener does know. It's not a "genuine" question - the speaker is just asking for cobfirmation that the listener understands what she's talking about.