A Pro-Hop is a move that is more formally known as the "jump-stop" or "jump-step." A jump-step is when you are driving or moving with the ball and then putting both hands on the ball to do a jump towards any direction you wish, landing on both feet at the same time.
If you don't land on your feet at the same time, it is considered a travel. After you land, you can only jump, pass, or score- not move. You cannot move at all after you land.