What are these light switches?
Better replace those LEDs with incandescent lights.

I recognize that switch. It is an X-10 brand, WS467 Dimmer module.



Here's the manual.

This switch can be controlled in person with your finger, or remotely with a plug-in or wireless controller.  Hopefully the seller left behind some controllers for you.  Otherwise you'd need to buy one to take advantage of remote control.

Basically the larger top momentary pushbutton is the normal on/off control.
The smaller bottom toggle is to 'lock' it off so that nobody can turn it on remotely.