In plain words
Pūraka means taking into us the air moving outside. Recaka means letting out the air taken in. Between the two, pūraka and recaka, is kumbhaka, that is, holding the air taken in for some time. For this there are 12 prāṇāyāmas. As for the form each prāṇāyāma takes: you must place the dakṣiṇāṅguṣṭha, that is, the thumb of the right hand, on the right side of the nose. Next, the second: the ring finger and this last finger, these two, you must place on the left side of the nose. In this way, keeping this right thumb here, you must breathe in air well through the left nostril 12 times. Then you must press this air you have breathed in firmly with these two fingers and hold it. As for how long to hold it: you must hold it as long as it takes to do three Gāyatrīs. That, they said, is one prāṇāyāma. What is one Gāyatrī? ‘Oṃ bhūr bhuvas suvaḥ tat savitur vareṇyaṃ bhargo devasya dhīmahi dhiyo yo naḥ pracodayāt’: one. The second: ‘Oṃ bhūr bhuvas suvaḥ tat savitur vareṇyaṃ bhargo devasya dhīmahi dhiyo yo naḥ pracodayāt’. The third: ‘Oṃ bhūr bhuvas suvaḥ tat savitur vareṇyaṃ bhargo devasya dhīmahi dhiyo yo naḥ pracodayāt’. Until you have repeated the Gāyatrī within yourself three times like this, you must press these two firmly and hold them. Until then this prāṇa stays held in kumbhaka. All this together, they said, is one single prāṇāyāma. In this way you must do 12 prāṇāyāmas. In the daytime you must do it standing. In the evening you must do it sitting. In this kind of prāṇāyāma there is great comfort. There is danger too. So you must practise this prāṇāyāma bearing in mind time, karma, cause and duty. It is not good to do prāṇāyāma when Manas is in unrest. Nor is it good to do it when your health has broken down. So what is the result that comes from prāṇāyāma? What comes from this prāṇāyāma is health and long life. For what purpose this health and long life?