I've always seen "ya ves" used as... "you see." So asking it ("¿ya ves?") would be the equivalent of... "you see?" For example:
Let's suppose a friend of yours thought he could get away with lying to his teacher. You try to advise him against it, but your friend, being as caprichoso as ever, still lies to his teacher. He winds up getting caught in his lie, and you tell him,
"¿Ya ves? ¡Te dije que le caía muy mal eso de mentir!"
"You see? I told you he really hates lies ( / lying)!"
Something like that. At least, that's how everyone around here uses it. I'm not sure if that's how it's used everywhere else.