The question asks what, if anything, makes a human life meaningful — and answers divide first over where meaning could come from. It may be conferred from outside, by a purpose the universe or its author assigns. It may depend on the objective worth of what a person gives themselves to. Or it may be made rather than found, in commitment, choice, lucidity, or revolt.
The question takes a particular form in traditions that inherit the collapse of older metaphysical guarantees, where it becomes whether meaning survives the loss of cosmic order at all; the answers gathered under absurdity and revolt address that sharpened version.
How one ought to live — the standard of right conduct — is a neighboring but distinct question, treated separately under The Basis of Right Action: a life can be lived well by an ethical standard and still confront the question of whether it means anything at all.