A mountain that can erupt molten rock, ash, and gases; a volcano or the geological feature/volcanic activity itself.
富士山は有名な火山です。
Mount Fuji is a famous volcano.
近くの火山が噴火したら避難してください。
If a nearby volcano erupts, please evacuate.
火山のふもとに小さな村がある。
There is a small village at the foot of the volcano.