Ok. So, first off, there are two kinds of power, AC (alternating current, which is the kind found in your house or that is provided by a generator) and DC (direct current, ie. provided by a battery).
AC has a hot, neutral, and a ground wire.
DC has a positive and a negative.
Regardless of whether AC or DC power is used, circuits work only when they’re closed. If the circuit is interrupted anywhere along that closed loop, current will no longer flow. A switch works by opening a circuit. So, when the light switch is closed, current flows from the house panel through the wires, through the light switch, and to the light bulb. When the switch is turned off, the circuit opens, and the light turns off. Or, when the button is pressed on a flashlight, the circuit is closed, and the light turns on.
Now. As stated earlier, your North American AC outlet has a hot, a neutral, and a ground wire. The hot wire is the path of travel for the current. The neutral completes the circuit, and allows unused current a “way home” so to speak. The ground wire acts as a safety net, preventing shocks and damage to equipment.
There’s WAY more to it, but that’s a decent start towards demystifying what the wires are, at least.