It means he likes the way you look, although you can assume he likes you or is at least interested in you. It's a pretty flattering compliment.
Not necessarily, but he definitely thinks your attractive. Or he could just be trying to get into your pants. Guys can be very manipulative. lol
If he is single then probably.. but sometimes when a guy says you're beautiful he's trying to be nice...
When a guy says you're beautiful?
When a guy says your beautiful does it mean he likes you?