One clue to what is meant by consciousness in Advaita Vedanta is deep sleep. Pure being, pure consciousness remains. In all our moments, gold itself is there. Similarly, in all these conscious experiences, pure consciousness alone is there. To understand what pure consciousness is by itself, we must purge our idea of various forms of ornaments.
Swami Sarvapriyananda teaches the Katha Upanishad, one of India's most revered texts which is also a part of the Vedas. It is a collection of philosophical poems representing a conversation between the sage Naciketas and Yama (god of death). They discuss the nature of Atman, Brahman and Moksha(liberation).