An LED toggle switch is a simple switch with an LED light in the handle of the switch which indicates the presence of current when it is turned on. When the light is on, the unit it is attached to is turned on. LED toggle switches are commonly found in automobiles and motorcycles. If you install an after-market lighting display on a licence plate, for example, the LED toggle switch is used to activate those lights or turn them off. Since you can't physically see the lights connected to the license plate, you can observe the LED toggle switch to make sure the lights are actually on.
If you turn the LED toggle switch to the "on" position and you don't see a light, it is an indicator that something is wrong and the lights are not working. LED toggle switches may have multiple lights installed to indicate different levels of use. If you have an LED toggle switch that can activate two rows of lights, the toggle may give you the option of lighting one row, the alternate row, or both together. It all depends on the type of LED toggle switch you purchase.