Do you know what a light switch is? It's something that can turn the lights on or off in a room, right? Well, a photoswitch is kind of like a light switch, but it works a little differently.
You see, a photoswitch is a tiny device that can change its behavior when it's exposed to light. Let's say you have a little toy car that runs on batteries. You could attach a photoswitch to the car, and then when you shine a flashlight on the switch, it would make the toy car start moving. When you take the light away, the switch would turn off and the car would stop.
But why would you want to use a photoswitch? Well, sometimes it's useful to have something happen automatically when the lights go on or off. For example, if you have a porch light that turns on when it's dark outside, you could use a photoswitch to make it happen without having to go outside and flip a switch. Or if you have a plant that needs a certain amount of light to grow, you could use a photoswitch to make sure it's getting enough light automatically.
So that's what a photoswitch is: a little device that can be used to control other things when the light changes. It's like having a little helper that can do things for you automatically when it gets dark or bright outside.