My favourite way to do this is to create callable functions so it looks like this:
To do this, create two functions, one for LightsOn and one for LightsOff. In the functions details panel select/tick “Call In editor”:
Then this is the functions for setting the light to visible (for pointlights)
Light on/visible function:
Lights off/hidden function:
The other way that eldany.uy already has shown is instead toggling all the pointlights in the level and sublevels, meaning that if a light is off, its gets set to on (and the other way), which is useful if you have different types of pointlights for day- vs night- time.