A skirt guard is like a fence for your bike wheel. It's a piece of metal or plastic that covers some or all of the wheel, like a big hoop. It's used to keep long and flowy things, like skirts or dresses, from getting caught in the spokes and chain of the bike. This can be really helpful especially if you're wearing a dress or skirt while riding your bike. It's like a special protector for your clothes while you're riding around town!