In plain words
Others, disciplined in food, offer the vital forces into the vital forces. All these know yajña, and through yajña their impurities are consumed.
Word for word
Others, with regulated food, offer the prāṇas in the prāṇas; all these too are knowers of yajña, whose impurities are destroyed by yajña.
The commentators
Bhagavadgītābhāṣyam
किञ्च —
अपरे नियताहाराः नियतः परिमितः आहारः येषां ते नियताहाराः सन्तः प्राणान् वायुभेदान् प्राणेषु एव जुह्वति यस्य यस्य वायोः जयः क्रियते इतरान् वायुभेदान् तस्मिन् तस्मिन् जुह्वति, ते तत्र प्रविष्टा इव भवन्ति । सर्वेऽपि एते यज्ञविदः यज्ञक्षपितकल्मषाः यज्ञैः यथोक्तैः क्षपितः नाशितः कल्मषो येषां ते यज्ञक्षपितकल्मषाः ॥ ३० ॥
In plain words
And there is more —
Others are 'of regulated diet' — that is, their food is limited and controlled; being so, they offer the vital airs, the various winds, into the breaths themselves. Whichever wind's mastery they have achieved, they offer the other winds into that very one — becoming, as it were, absorbed into it. All of these, too, are knowers of sacrifice, 'whose taints are consumed by sacrifice' — meaning that through the sacrifices just described, their taint has been consumed and destroyed.
Close to the Sanskrit
And what further —
Others, 'of regulated diet' — regulated, that is limited, food, of whom — they are of regulated diet; being so, the vital airs, the various winds, into the breaths themselves they offer — whichever wind's mastery is achieved, the other winds they offer into that very one — they become, as it were, absorbed there. All of these too are knowers of sacrifice, 'whose taints are consumed by sacrifice' — by the sacrifices just described, consumed, destroyed is the taint of whom; they are those whose taints are consumed by sacrifice.