What does putting something on the back burner mean? And how could that term be misunderstood?

Answer 1

Let's say you're making a meal, and you need to occupy the front and back burner at once because you have too many dishes to cook to do one at a time. It is most convenient for the item that needs to be done first, to be put in the front burner. The item that takes longer to cook, or is of lesser importance can go to the back.

Answer 2

When you put food on the back burner, you let it slowly simmer, knowing it won't be ready for several hours. In the old days, some cooks always kept a stock pot simmering on the back burner, adding bits of meat and vegetables as they became available.

As a metaphor, when you put something on the back burner, you're basically putting it aside and probably forgetting about it.

The question might be -- how soon are you going to do something about whatever it is on the back burner.