What is Brahman:
Brahman is the Absolute Reality or universal substrate (not to be confused with the Creator god Brahmā) is said to be eternal, omnipotent, omniscient, omnipresent, and ultimately indescribable in human language. The sage-seers of the Upanishads had fully realized Brahman as the reality behind their own being and of everything else in this universe. They were thus Brahmins in the true sense of the word. These rishis described Brahman as infinite Being, infinite Consciousness, and infinite Bliss (satcitananda). Brahman is regarded as the source and essence of the material universe. The initial unmanifest state of singularity of the universe is described as a beyond being and non-being in the Nasadiya Sukta. The Rig Veda says that by the desire of the Supreme Being (RV 10.129.4), the initial manifestation of the material universe came into being from Hiranyagarbha (literally "golden womb"), out of which all worlds, organisms and divine beings (devas) arise:
"Great indeed are the devas who have sprung out of Brahman." — Atharva Veda