Meaning of the word "on duty" in English

What does "on duty" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

on duty

US /ˈɑn ˈduː.ti/
UK /ˈɒn ˈdjuː.ti/
"on duty" picture

Phrase

working, especially when one is a police officer, a soldier, or a medical worker

Example:
The police officer was on duty for twelve hours.
Nurses are always on duty, even on holidays.