Gaulish was a language spoken a long, long time ago by a group of people who lived in a place called Gaul. You may not know where Gaul is, but it's a place that is now part of some countries in Europe.
Gaulish is different from many languages we know today, but it was similar to other languages that existed at that time. Gaulish was spoken by people who lived during a time when there were no phones or computers, which means they didn't write down their language as much as we do today.
Today, we don't hear much of Gaulish because it's not a language that people speak anymore. But it was important for people who lived in Gaul because it helped them communicate with each other and share their thoughts, feelings, and ideas. Their language helped them preserve their history and culture, and learn from each other in their communities.