What is the quick action button "Lock" and the departure switch used for on my VELUX ACTIVE?

The lock button and departure switch are used to place the VELUX ACTIVE indoor climate control into a secured mode (away) when the home is empty. Pressing the "closed lock" sets the secured/away mode. Pressing the "open lock" sets the unsecured/home mode.

Note: Setting the states in the app is the same as pressing the departure switch.