What does it mean when the light is on/off on whatever the item is?

TVs have a “Stand By” light that is on when the TV is shut-off.

Dark Room: light (outside) is on > don’t go in.
Light (outside) is off > you may enter.

Usually, when the white/clear lights are on on the back of a car or truck, the vehicle is backing up or is in reverse preparing to back up. In some cases the bulbs are burnt out or the fuse is blown or the switch is bad or the wiring is faulty, and the vehicle will back up anyway,

Some waffle makers have an indicator light to tell you that the waffle has been cooked.

Ok. When the light is on on a vending machine it means it’s empty.

My Hitachi TV displays a red light when it is off. When the TV is turned on, the light goes off.

My Oster waffle maker turns on a red light when it is warming up. When the waffle maker is ready, the light turns off.

When you turn the car key to the point where the engine is normally running, and all of the dash lights come on, this is a test mode for those dash lights to show you that they are working. When you start the car and start driving, they should go out.

Ok. Is there a circumstance/an item when the lights on or off, and the the opposite information is sent because the light fixture is out of order and the consequence could be fatal?

My electric stove has two separate lights. One tells you a burner is on and one tells you the stove is hot. So, the hot indicator can actually be on when the stove is off, because the burner stays hot for a while after shutting it off.

How about if the light feature is out of order?

If it’s out of order then I can still tell if it’s on by the position of the knob I use to turn it on or off.

My mom raised me to always assume a stove or oven is hot, so that’s what I do.

Ok.