what does this mean

It could mean several things. For example, it could be a humorous version of the belief that art should be evaluated in terms of its internal and formal features rather than in terms of its function. In this sense, it is a sort of paraphrase of Kant, who defined aesthetic beauty as that which appeared to have "purposenesss without purpose."

Or it could be a way of saying that art is largely a luxury item for the materially affluent. That is one of the themes of the book from which the quote is taken, after all.

What it says. It has no use at all.