For he is the Breath shining forth in all beings, and he who understands this becomes truly wise, not a talker only. He revels in the Self, he delights in the Self, and having performed his works (truthfulness, penance, meditation, &c.) he rests, firmly established in Brahman, the best of those who know Brahman.

In plain words: The Lord is the life-breath shining in every being. Whoever understands this becomes truly wise, not just someone who talks about it. They find joy and delight in the Self. After doing their duties, such as being truthful, disciplined and meditating, they rest firmly in Brahman as the best of those who know it.