It is very simple it means that the he finds the girl to be pretty.
That may not be pourpouly in a negative sense of physical attraction.
It can be made out if it is in some negative sense if the boy had any affair earlier and things like that.
If a guy says that you are pretty it does not mean that he likes you. He could like you, or he could just be paying you a compliment.
It means that you are really pretty.
He is saying that you are hot.
If a guy says that he thinks you will look pretty in a dress, he means that the dress will best bring out(magnify) your beauty.
That he's got good eyesight
I means that you are special to him and that you are very pretty
It means he thinks your pretty obviously but he might like you or hes just a nice guy who likes to compliment people.
"Thank you"
It only means the guy is ugly for you or the guy does not have a big account in the bank.
It means that he has just seen MATRIX and is pretty excited about it.
He pretty much told you with what he said...
It's a pretty straightforward message, if he was saying it seriously.