Typically 3 or 4 pins
Common configurations:
2-pin: simple ON/OFF (no lamp)
3-pin: ON/OFF + indicator lamp (most likely this one)
4-pin: DPST (switches live & neutral)
For the illuminated type (3-pin):
COM / Live input
NO / Load output
Neutral (for the lamp)
Power switch for:
Air-cond accessories
Water pumps
Power supplies
DIY control panels
Indicator lights up when switch is ON