diśām — of the directions; tvam — You; avakāśaḥ — the power to accommodate; asi — are; diśaḥ — the directions; kham — the ether; sphoṭaḥ — elemental sound; āśrayaḥ — having (ether) as its basis; nādaḥ — sound in its form of unmanifest vibration; varṇaḥ — the primeval syllable; tvam — You; oṁkāraḥ — om; ākṛtīnām — of particular forms; pṛthak-kṛtiḥ — the cause of differentiation (namely, manifest language).

Translation

“You are the directions and their accommodating capacity, the all-pervading ether and the elemental sound residing within it. You are the primeval, unmanifested form of sound; the first syllable, om; and audible speech, by which sound, as words, acquires particular references.”

Bhaktivedanta Purport

By Śrīla Prabhupāda

In accordance with the general process of creation, speech always becomes audible in stages, which proceed from subtle inner impulse to outward expression. These stages are mentioned in the mantras of the Ṛg Veda (1.164.45): catvāri vāk-parimitā padānitāni vidur brāhmaṇā ye manīṣiṇaḥguhāyāṁ trīṇi nihitāni neṅgayantiturīyaṁ vāco manuṣyā vadanti “Discriminating brāhmaṇas know of four progressive stages of language. Three of these remain hidden within the heart as imperceptible vibrations, while the fourth stage is what people ordinarily understand as speech.”