। ॥ ३९ ॥
In plain words
As the Tripuṭī—the knower, knowing, and known—fades, it dissolves in Brahman. Everything here is only Manas, mind; and Manas itself is only Jñāna, pure awareness.
Close to the Sanskrit
The Tripuṭī—the triad—wanes away and reaches Brahma-nirvāṇa, extinction in Brahman. All this is Manas alone; that Manas is Jñāna alone.