What exactly does the fire in the hole mean?

On the surface, it means "there is a fire in the hole"

But it actually has many different meanings.

In the professional military terminology of the US military,

fire

exist

this

hole

Pretty good code word

Hint at teammates

I'm going to throw a Grenade.

get rid of

There are many different other explanations.

take for example

Fire there.

Fire into the hole

...