This is the oil-jug concept. We must imagine that Every baby was born with a jug of oil (theoretically).

Throughout your life, whenever you do a bad deed, a drop of oil adds to the container.

Whenever you do a good deed, a drop of oil leaves the container.

The objective is to have no more oil in the jug when you die, meaning you did more good deeds than bad. If you do have oil left in your jug, you will be sent to hell where you will be used as cooking oil for the AC or heater that the people in Jannat need.

The ACs and heater have to be powered somehow, and that will be by the oil in your jug.