। ॥ ५५५ ॥
In plain words
Even while he is still alive, he is already free, already fulfilled - this greatest of the knowers of Brahman is already Brahman. When the last trace of the body-mind falls away, he simply arrives at what he already was: the real, non-dual Brahman.
Close to the Sanskrit
Ever liberated even while living, his purpose fulfilled, the best knower of Brahman - who is already Brahman - upon the fall of the limiting adjunct attains the real, non-dual Brahman.