ओंकारः स्वर्गद्वारं तस्माद्ब्रह्माध्येष्यमाण एतदादि प्रतिपद्येत ।विकथां चान्यां कृत्वा एवं लौकिक्या वाचा व्यावर्तेत ब्रह्म' ।'प्रणवाद्यास्तथा वेदाः प्रणवे पर्यवस्थिताः ।वाङ्मयं प्रणवः सर्वं तस्मात्प्रणवमभ्यसेत्' इत्यादिस्मृतिभ्यश्च विश्वशब्देन ओंकारोऽभिधीयते ।वाच्यवाचकयोरत्यन्तभेदाभावात् विश्वमित्योंकार एव ब्रह्मेत्यर्थः ।'सर्वं खल्विदं ब्रह्म तज्जलानिति शान्त उपासीत' इति ।एतदुक्तं भवति—यस्मात्सर्वमिदं विकारजातं ब्रह्म तज्जत्वात् तल्लत्वात् तद
In plain words
The syllable Om is the gateway to heaven. Therefore, one who is about to study the Veda should begin with it, turning away from ordinary worldly speech and idle talk. Texts declare that the Vedas begin with Om and rest in Om, that the entire realm of speech is Om, and therefore one should meditate upon Om. Through such scriptural passages, the term Viśva denotes the syllable Om. Because there is no separation between the name and what it names, Viśva is Om itself—Brahman. As the scripture says: 'All this verily is Brahman; let a tranquil person meditate upon it as originating, subsisting, and dissolving in Him.' The import is this: because all these changing forms are Brahman, originating and dissolving in Him...
Close to the Sanskrit
The syllable Om is the door to heaven; therefore, a student about to study the Veda should commence with this. Desisting from other idle talk with worldly speech, 'Brahman.' 'The Vedas and others start with Om and are established in Om; speech is entirely Om; therefore one should practice Om'—from such smritis also, the syllable Om is designated by the word Viśva. Because there is no absolute difference between the name and the named, the meaning is that Viśva is Om itself, which is Brahman. 'All this verily is Brahman, calm, let him meditate upon it as born from that, etc.' This is what is said: because all this array of modifications is Brahman, due to being born from it, dissolving in it, and...