A Timer is used to delay the execution of the connected action. For example, you may wish to display a notification on your page for a few seconds, then remove it. Put a Timer before the removal action in your code flow to delay the removal.
Timers are measured in milliseconds, so if you want to delay for 3 seconds, that is 3000 milliseconds.
Note: The timer does not halt the script, it simply sets up a timer to wait for the desired time, then executes the function. So if you have other functions running, for example, maybe you had a Splitter further up the Workflow, other branches of your script will not be affected by the timer.