This trick is made of two words. Varial and Kickflip. A varaible would be a complete 180 horizantal rotation of the board. A kicklip would be a complete rotation of the board. When the board rotates you should see the underside. When these two manuevers combine you have formed a Varial Kickflip. That was a freakin' huge definition and I'm surprised you stuck around for the whole thing.