Farore's Wind is Zelda's Up B move.
A yellow ribbon of magic spins around Zelda, causing her to disappear. After that, she will reappear in the direction held on the control stick (or up if the control stick is not moved). The initial ribbon spinning is capable of damaging opponents that touch it. In Brawl, this attack also creates a small explosion (similar to the one made by the initial part of Sheik's Vanish) upon reappearing, dealing some damage and knockback.
It is based on a spell with the same name from The Legend of Zelda: Ocarina of Time. Link could use to mark a place in a Dungeon and then return to that warp point at a later time.