Fetching details from the dictionary...
order (esp. to a number of people); command
ritual of bowing at start and end of school class
教官が新兵に号令した。
The instructor commanded the new recruits.
先生の号令で生徒が動いた。
The students moved at the teacher's command.
社長の号令一下、チームは動き出した。
At the CEO's command, the team started to move.