"wings" refers to the part of a pad that folds around to snap the pad onto your underpants.

Wings on a cloth pad help to keep the pas in the right position in your underwear, prevent the pad from falling out when you pull your underpants down (for toileting or getting changed) and to catch any flow that would otherwise leak off the sides of the pad.

Not all pads have wings. Cloth pads without wings are called wingless pads, and may use other methods to help prevent them slipping in your underwear (such as "grippy" fabrics).
