Dugout has two main meanings:

1. A shelter dug into the ground or carved into a hillside, often covered with earth or logs. Early settlers on the Great Plains sometimes lived in dugouts carved into hillsides because wood was scarce and dugouts stayed cool in summer and warm in winter. Soldiers in wartime have used dugouts for protection. These underground shelters work well because the earth itself provides insulation and safety.
2. In baseball and softball, the dugout is the long, low bench area where players and coaches sit during a game when they're not on the field. Called a dugout because it's usually built a few steps below ground level, this sheltered area helps protect the team from foul balls while keeping them close to the action. You'll see players filing out of the dugout when it's their turn to bat and returning after they've completed their at-bat. Each team has its own dugout, one along the first-base line and one along the third-base line.

Both meanings share the idea of a protected space that's lower than the surrounding ground.