The noun relief means "the act of reducing something unpleasant," like medicine that brings relief from your terrible headache.
Relief has several meanings. It can refer to help or assistance, like disaster relief, or a change for the better: it was a relief when you finally found your car keys. Relief also means "someone who takes the place of another," like a relief pitcher who steps in to finish the game. A relief is also a type of sculpture with shapes carved to stand out from the background.