The height of a candle depends on the amount of time the candle has been burning

the dependent component will be the height.
you grab a candle, and it has a height of hmmm 7 inches say, and then you light it up, as the independent component of time goes by, the height is shortening, so the height is dependent on the time in order to be either taller or shorter.
so height of the candle being dependent on such, is the range of such function.