The Indication LED has its own 2 Pins, it can be turned on by 12-24V Power and can be controlled independently from the switch. If you are controlling a 12-24V Load through the switch, you can connect the output of the switch to the LED pins and light up the LED only when the switch is on.
This is an SPST Single pole switch with C, NO, and NC terminals. This allows you to control up to 1 device or load wires independently. If you use an SPST switch for input power or battery power input you can switch live power wire using this switch for power isolation when the switch is off.