Nostr is like a big playground where different people can come and play games. But instead of physical games, they play with digital money called cryptocurrency. People can buy and sell this digital money on Nostr.

Relays are like helpers that help people buy and sell digital money. Imagine you want to buy a toy from a store, but you're too short to reach it. A nice big person can help you reach the toy and buy it for you. That nice big person is like a relay on Nostr. They help people buy and sell digital money safely and easily.