Noob question :)

[Captain_Smith]

Under the engine control of a 737, it has

in red: 1 APU 2

It says APU fire supression.

What does this do? and what is supression?

[Airliner]

Fire extinguisher in case you have a fire in the APU - same as the engine fire system. Pull the handle to fire a bottle and hopefully put out
the fire.

[Captain_Smith]

Ahh, I see.

Thanks !