Cisalpine Gaulish is a language that people used to speak a really long time ago in a place called Cisalpine Gaul. Cisalpine Gaul is an area in Europe that is now part of Italy. Back then, people didn't speak Italian like they do now. They spoke a language that was different from Italian, and that language was Cisalpine Gaulish.
So imagine you're playing in your backyard with your friends, and you all speak English. But then a new kid moves in, and they speak a different language that you've never heard before. That's kind of what it was like for the people in Italy when they met the Cisalpine Gauls. They had to learn a new language because the Cisalpine Gauls didn't speak Italian.
The Cisalpine Gauls were really good at making things out of metal, like swords and shields. They also were really good at farming and growing crops. So they traded with the Italians, and they taught each other things they didn't know.
But eventually, the Cisalpine Gauls were conquered by the Romans, and they started speaking Latin instead of Cisalpine Gaulish. So the language kind of disappeared over time, but we know about it because people wrote about it and studied it.