An anti-war film is a movie that tells a story about how war is bad and we should try to avoid it. Think of war like a big fight between two groups of people who really don't like each other. In an anti-war film, the story is about trying to stop the fight and find a way for everyone to get along.
The movie might show some of the bad things that happen during a war, like people getting hurt or killed, homes being destroyed, and families being separated. It might also show how hard it is for soldiers to be away from their own families and how they can be scared and hurt too.
The point of an anti-war film is to help people understand why war can be such a bad thing. Sometimes people might think that going to war is the only way to solve a problem, but watching an anti-war film can help them think about other solutions that might be better for everyone involved.