Timers can be used to keep track of how long you are spending on certain tasks. There are two main ways to create a timer: 1) By click on the 3 dots menu located to the left of a work item, or 2) By clicking the dropdown menu next to the timer in the main header bar.
Any timers that you have created will show up in the timers menu as shown above. To start a timer simply click the green play button. A running timer can be either paused or stopped. Pause the timer if you plan to log more time against it later. Stopping a timer will save it as a time log entry and remove that timer from your list of timers.