Layer of fabric at the lower edge of the sleeve of a garment
A cuff is a layer of fabric at the lower edge of the sleeve of a garment (shirt, coat, jacket, etc.) at the wrist, or at the ankle end of a trouser leg. The function of turned-back cuffs is to protect the cloth of the garment from fraying, and, when frayed, to allow the cuffs to be readily repaired or replaced, without changing the garment. Cuffs are made by turning back (folding) the material, or a separate band of material can be sewn on, or worn separately, attached either by buttons or studs. A cuff may display an ornamental border or have lace or some other trimming.
https://en.wikipedia.org/wiki/Cuff