This is as simple as the description says. Just do 7 Prince Hops (flick your controller up and you'll see your character hope into the air and make a boing sound) before you finish the level. I did it exactly 7 times and got the trophy to unlock. Make sure to be extra careful that you don't do it an eighth time or the trophy might not unlock (not 100% sure on this yet). I suggest waiting until time is almost up to do the 7 Prince Hops and then waiting until the level is over. This can be done with The Prince and any of the cousins.
The trophy will unlock once you Trophy Update is finished and you're returned back to the Village Square.