This is the room that the detachment for the citadel guard will be stationed as a 24-hour rotation that you're on, so you started at 10 o'clock in the morning, and you're due the end of 10 o'clock the next morning.

この部屋は要塞の見張りのための分室です。警備員は24時間交代で任務につきます。朝10時に勤務開始で翌朝の10時までです。