Clad means "dressed or covered." Most kids go to school clad in jeans and t-shirts, but students in the Shakespeare club might show up clad in velvet gowns or leather breeches.
As a verb, clad is the past tense and past particle of “clothe,” as in “the leprechaun clad himself in green.” It’s also an adjective that describes being covered or clothed, so a building can be clad in brick, while a person can be clad in head-to-toe sequins. It’s an old-fashioned word, kind of like “shod,” which means “wearing footwear.”