अथ खलु य उद्गीथ स प्रणवो य. प्रणव स उद्गीथ इति होतृषदनाद्धैवापिदुरुद्गीतमनुसमाहरतीत्यनुसमाहरतीति ॥
In plain words
Now then, whatever the udgītha is, that is the praṇava; and whatever the praṇava is, that is the udgītha. From the seat of the Hotṛ priest, he repairs even a flawed recitation of the chant—yes, he repairs it completely.
Close to the Sanskrit
Now indeed, what is the udgītha that is the praṇava, and what is the praṇava that is the udgītha—from the seat of the Hotṛ indeed he rectifies even a badly chanted udgītha, yes, he rectifies it.