He opened the door quietly.

Meaning: This sentence describes someone moving a hinged, sliding, or revolving barrier at the entrance to a building, room, or vehicle, or in the framework of a cupboard so that there is a space or passage.

Choice of Words: Opened means to move something so that there is a space or passage. Door is a hinged, sliding, or revolving barrier at the entrance to a building, room, or vehicle, or in the framework of a cupboard.