timer
nounUK /ˈtaɪmə/
US /ˈtaɪmər/
A timer is a thing that counts time for you.
Set the timer for ten minutes so the cookies don't burn.
OTHER MEANINGS
2. A device that turns something on or off at a set time.
The sprinkler timer waters the garden every morning.
3. A person who records how long something takes.
The timer stood at the finish line with a stopwatch.
4. A part of a computer program that schedules tasks.
The app uses a timer to save your work every minute.