It is the panel outside of the elevator. "Fart" means speed and "I fart" means that the elevator is moving. Hertil means "to here" and is the button you use to summon the elevator to your floor.

Mein teil is when you have a friend over and you feel like barbeque, but the fridge is empty.

"I fart" means "in movement", just an indicator that it's on its way, and "hertil" is as you guessed a combination of "her til" meaning "to here", that's the button you press to call the elevator.