This event will check the status of the timer selected in the menu. That timer should have been configured before on the action side of another automation (Action type Periodical).
For example: if it is desired to take a photo 10 seconds after the takeoff, one automation should have the event of Phase take off, with the correspondent Periodical action that will start a timer that lasts 10 seconds. Then with another automation, indicating in the event the timer created, an action is created to take a photo when the timer event is triggered. In Timer is selected the number that identifies the timer that is evaluated in this event.