Used as a verb it means to bleach the hair and remove current color.
When used as a noun it refers to the chemical composition designed to remove color from the hair. Bleach is sometimes referred to as a pre-lightening or decolorizing treatment.
Daily Hair Tip
With any hair care products it is important to remember that a little goes a long way. Overuse of any products can make hair look lank, oily or greasy.