what do this phrases mean "here you go" and you are welcome"?
I have just read a dealog and did not understand what this phrases mean, here is this one.

Susan : David, would you like something to eat?
David : No, I'm full.
Susan : Do you want something to drink?
David : Yes, I'd like some coffee.
Susan : Sorry, I don't have any coffee.
David : That's OK. I'll have a glass of water.
Susan : A small glass, or a big one?
David : Small please.
Susan : Here you go.
David : Thanks.
Susan : You're welcome.

Question

what do this phrases mean "here you go" and you are welcome"?
I have just read a dealog and did not understand what this phrases mean, here is this one.

Susan :	David, would you like something to eat?	
David :	No, I'm full.	
Susan :	Do you want something to drink?	
David :	Yes, I'd like some coffee.	
Susan :	Sorry, I don't have any coffee.	
David :	That's OK. I'll have a glass of water.	
Susan :	A small glass, or a big one?	
David :	Small please.	
Susan :	Here you go.	
David :	Thanks.	
Susan :	You're welcome.

Answer

You can say "Here you go" as you give something to someone. Susan would have been giving David the glass of water he asked for as she said that.

"You're welcome" is the standard response to "thanks" or "thank you". You might have been taught "any time", "no worries", "no problem", or "Don't mention it" instead.

Answer

you're welcome = არაფრის

Answer

In U.S. English, "Here you go" means "I'm giving you what you asked for." In tone, it is informal, cheerful, and friendly. 
When someone performs any kind of service, even a small one, it is polite to say "Thank you." Whenever someone says "Thank you" to you, it is polite to reply "You're welcome." As Jmat says, this is a standard pattern, almost a ritual. In the U.S. the best and most common response to "Thank you" is "You're welcome."