In the Schedules screen, you can activate the presence simulation. Once activated, it will disable all of your existing schedules, and enable automated schedules turning the lights of the home On in the morning, then Off, and On in the evening then Off.
The purpose is to simulate a human presence in the home, especially if you are far away from it in order to provide an easy "light security".
You can de-activate the presence simulation at any time. This will restore all your usual scheduled events.