तिर्यगूर्ध्वमधः पूर्णं सच्चिदानन्दमद्वयम् ।अनन्तं नित्यमेकं यत्तद्ब्रह्मेत्यवधारयेत् ॥ ५६ ॥
In plain words
Full to every side — across, above, below; being, consciousness, bliss, with nothing second to it; endless, eternal, one. That is Brahman — settle on it with certainty.
Close to the Sanskrit
Full sideways, above, below; being-consciousness-bliss, without a second; endless, eternal, one — that which is such, that one should ascertain as 'Brahman'.