An enhancement makes something better. An enhancement to your recipe makes it taste better. An enhancement to your outfit makes it look snappier. An enhancement to your camera lens makes it take clearer photos.
The noun enhancement comes from the verb enhance, meaning "to increase or improve," and it can describe anything that's an improvement to the quality or value of something. People might make surgical enhancements to their faces and bodies to make themselves look better — otherwise known as plastic surgery — although this type of enhancement that is somewhat controversial. Those who do it believe it's an enhancement to their quality of life, since they feel better about themselves.