It's saying "Mine" and "I love you". My cats do this, too. I love it :)
My kitty does it too it means he loves you :3
he is showing affection
It is his way of protecting you . You are loved by your kitty
From my experience from cats and dogs they do that because they want something. Usually you to pet them but it could be food or something.
It's a protection thing. Cats like to have their paw on top of your hand. I've tried this with my cat several times. Every time I put my hand on him or on his paw, he puts his paw on top of my hand.
Look :) http://www.youtube.com/watch?v…