I'm curious what does a telefunken tube do anyways?

Telefunken is just a brand. A tube is almost like an electron valve.

Like an on and off switch?

Basically the same thing as a transistor. But older
You can use both as an switch. But mostly, they're used as an "current regulator". A transistor (and a tube) is a device used to amplify and switch electronic signals. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal.

It all makes sense now!

Hmmmm
I might have the same one somewhere, gonna check that someday