五彩 literally means 'five colors' (blue, yellow, red, white, black in traditional Chinese color theory), but it's used more broadly to describe anything that is multicolored or brightly colored, especially in traditional art, festivals, and nature. You'll often see it in the idiom 五彩缤纷 (wǔcǎi bīnfēn, 'a riot of color') and in references to 五彩瓷器 (wǔcǎi cíqì, 'five-color porcelain'), a famous style of Chinese ceramic. As a noun, it refers to the concept of five colors or multicoloredness, but it's frequently used attributively (like an adjective) before nouns.