Yes, it has to do with the TileSet terrain feature (which used to be called autotiling). You can read about how it works & how to use it in the Godot docs: https://docs.godotengine.org/en/stable/tutorials/2d/using_tilesets.html#creating-terrain-sets-autotiling

Basically instead of selecting each tile you need separately, you can just “paint” and Godot will automatically select the correct tiles to use for floors, walls, etc. Super useful when making maps!