A battalion aid station is like a special room where doctors and nurses help soldiers who have been hurt or sick. It's like a really strong and safe house where the soldiers go if something happens to them.
Inside the battalion aid station, there are beds and special equipment to help the doctors check how the soldier is doing. There might also be medicine and special things to help the soldier feel better.
The doctors and nurses who work in the battalion aid station are very smart and know a lot about how to help people who have been hurt. They work hard to make sure that the soldiers feel better and can go back to doing their important job of protecting their country.