A chastity cage is a special kind of underwear for grown-ups that can be worn by either men or women. It's designed to cover up the private parts to make sure they can't be touched or played with.
The cage is made of a hard material like plastic or metal, and it's put on like a regular pair of underwear. But instead of just covering up the private parts, it also has a special part that goes over a man's penis to keep it from getting hard or being touched, or a part to go in a woman's vagina to keep it from being penetrated.
The idea behind wearing a chastity cage is that it helps the person wearing it to control their sexual urges or desires. It's often used by people who want to practice self-restraint, discipline, or submission. Some people even wear a chastity cage as part of their sexual fetishes or role-playing games.
Whatever the reason, it's important to remember that wearing a chastity cage should always be something that's agreed upon and consensual between all parties involved.