Alright kiddo, so have you ever heard of a language that nobody speaks anymore? That language is called an extinct language. It means that the language is no longer used or spoken by people.
Think of it like a really old toy that nobody plays with anymore because they found new toys that they like better. That old toy is the extinct language, and the new toys are the languages that people use today.
Some languages become extinct when the people who speak them die out or start using a different language. Other languages become extinct when the culture they were a part of disappears or changes a lot.
It's kind of sad when a language becomes extinct because it means we can't learn from that culture anymore. But sometimes people work hard to keep old languages alive by teaching them to new generations.