The Stairwell Lighting Switch node, when the Input connector value is 1, sends 1 to the Output connector and then starts a timer, at the expiration of the timer it sends 0 to the Output connector.
The timer is set to the time defined in the Time for ON property of the node and if the property Retriggerable is enabled, the timer restarts whenever the Input connector receives 1.
If the property Manual OFF is enabled, when the Input connector value goes to 0 the node sends 0 to the Output connector and automatically stops the timer; otherwise the expiration of the timer is the only condition to send 0 to the Output connector.
The Warning connector value goes to 1 before the timer expires until the Output connector is 1. The time for warning is specified through the Warning before OFF property.

 Behaviour of Stairwell Lighting Switch

Behaviour of Stairwell Lighting Switch