In plain words
Since Vāyu is present in all things, they call it advartha. Advartha means one and a half; that is its meaning. Next she asked whether he could name it as one god. That very one is prāṇa, he said. Ekohaṃ bahaśyāṃ: what is, is one alone, yet He Himself takes on form in many ways, wills it of Himself, and shapes Himself into different forms. Though what is, is one alone, many sages see it in many forms and set up many names. Ekaṃ sat viprābahudhā vadanti: the Satya that is, is one alone, but they shape it into many forms. Gārgī was delighted at this: this man is a knower of Brahman. Saying he was fit to stay at Mahārāja Janaka's court, she prayed Janaka to make him its peerless scholar. Yājñavalkya did not end his discourse at that, but set about teaching everyone there plainly.
A mother loves her child. The child loves the mother. A wife loves her husband. The husband loves his wife. The elder brother loves the younger. The younger brother loves the elder. In the very same way, some love wealth. Some love things. Some love learning. For whose sake do they love, and who is it that loves? The husband does not love his wife for the wife's sake. A mother does not love her child for her child's sake. Each loves for his own sake; no one loves another for the other's sake: that was his conclusion. All these affections are bound up with affection for the Ātma. But they are not bound up with affection for the body. Now I love this thing. Do I love this thing for this thing's sake? I love this thing for my own sake. In the same way, when people love all the objects there are in the world, they do not love the thing for the objects' sake. They love that thing for their own sake. What does it mean to love oneself? They are only showing forth their own affection for the Ātma.
What is the Ātma? It is the vast form of these three, speech, Manas and prāṇa. Where has prāṇa come from? Where has Manas come from? Yājñavalkya said, “Of the food man eats, what is gross takes the form of excreta, and what is most subtle takes the form of Manas. Of the water man drinks, what is grossest takes the form of urine, and what is subtle takes the form of prāṇa. Speech takes on a radiant form. The radiance called speech dedicates the body made of food to the prāṇa made of rasa.” “Manas, speech and prāṇa: the joining of these three is what you call the Ātma, is it not?