HOW to make a character fly up in the air with velocity then fal right back down when hit?

hit I made a Special Fire move script wich allows the player to kick the opponent with it's leg on fire. when hit I want the opponent to fly up in the air...… is their any way to do that?

You can use a VectorForce constraint attached to RootRigAttachment to send the player flying in whatever direction - then, after some x seconds, destroy it to allow them to fall back down.