अथ खलु य उद्गीथ स प्रणवो यप्रणव स उद्गीथ इत्यसौ वा आदित्य उद्गीथ एष प्रणव ओमिति ह्येष स्वरन्नेति ॥
In plain words
Whatever the udgītha is, that is the praṇava; and whatever the praṇava is, that is the udgītha. This very sun is the udgītha, and this is the praṇava; for this one moves onward sounding oṃ.
Close to the Sanskrit
Now indeed, what is the udgītha, that is the praṇava; and what is the praṇava, that is the udgītha. Thus, that indeed sun is the udgītha, this is the praṇava; because sounding with oṃ this one moves.