In plain words
The Praṇava that sounds in the heart of the universe: hear it with śraddhā, to the joy of your ears. This indeed is the kalpaka tree that grants both your desires and Mukti; do not forget so good a word.
Vedānāṃ sāmavedo'smi. “Among the Vedas, I am the Sāmaveda,” declared the Teacher of the Gītā. “Sāmnā udgīto rasaḥ,” said the Chāndogya Upaniṣad. Within the Sāmaveda, this Sāmaveda shines forth as the embodiment of rasa, the embodiment of Prema, the embodiment of the divine. Udgītha means the Praṇava itself. The very rasa of the Sāmaveda is the Praṇava. The Praṇava is the very life.
Oṃkāraṃ sarvavedānām: in all the Vedas it has made the Oṃkāra known, holding it to be the foremost. From this we must understand how exalted the Oṃkāra is, how sacred, how important. In the world of letters, the Oṃkāra, the single syllable, is what makes all the letters manifest. The Praṇava is another name for the Paramātma. The Sāmaveda is the very embodiment of such a Praṇava. Vyāsa first taught the Sāmaveda to the sage Jaimini. He taught it to his disciples, and those disciples to theirs; growing in this line of disciples, it took shape as many branches. This Sāmaveda, which flourished in a thousand branches, has by now sunk into the womb of time, and at last only three branches remain. Kaudhima is one branch. Rāṇāyani is the second branch. Jaimini is the third branch. This Kaudhima branch lives on today among the Nāgara brahmins in Gujarat. The Rāṇāyani branch lives on in Maharashtra. What remains is the Jaimini branch. This one shows itself in the state of Karnataka. Between these two branches, Kaudhima and Rāṇāyani, not many differences are seen. When this Kaudhana branch recites the word ha, urā, ni. The Rāṇāyani branch: ā ā ū rā. nī.., it says, and goes on giving every one of them a long vowel. Rāṇāyani is the one with the long vowels. Kaudhima is the one that lengthens only some and says the others short. Though it is only a small branch, it is an important one. It comes in two kinds. The two kinds are arcani and gāna. Within this gāna there are four kinds. Grāmīṇa-gāna; araṇyaka-gāna, which means the singing done in the forest. The third is ūhā-gāna. The fourth is ūhya-gāna.