Actually ELI5: You know those really old buildings with a paddle wheel on the side, sitting in a river? The river water pushes the wheel to turn it, and then we can connect the wheel to stuff like a sawmill or whatever.

Now, let's say you want to have a sawmill down the road instead of right on the river. If you're smart, you can find a way to stick a big hose in the river and take all that water to the other sawmill, and push a wheel there, then use another hose to put the water back in the river. That's basically what a wire does.