Mahāvākya

The Mahavakyas (sing.: mahāvākyam, महावाक्यम्; plural: mahāvākyāni, महावाक्यानि) are "The Great Sayings" of the Upanishads, as characterized by the Advaita school of Vedanta.

Most commonly, Mahavakyas are considered four in number,

Though there are many Mahavakyas, four of them, one from each of the four Vedas, are often mentioned as "the Mahavakyas". According to the Vedanta-tradition, the subject matter and the essence of all Upanishads is the same, and all the Upanishadic Mahavakyas express this one universal message in the form of terse and concise statements. In later Sanskrit usage, the term mahāvākya came to mean "discourse", and specifically, discourse on a philosophically lofty topic.

According to the Advaita Vedanta tradition the four Upanishadic statements indicate the ultimate unity of the individual (Atman) with Supreme (Brahman).

The Mahavakyas are:

People who are initiated into sannyasa in Advaita Vedanta are being taught the four [principal] mahavakyas as four mantras, "to attain this highest of states in which the individual self dissolves inseparably in Brahman".

Several translations, and word-orders of these translations, are possible:

Prajñānam:

Prajñānam as a whole means:

Related terms are jñāna, prajñā and prajñam, "pure consciousness". Although the common translation of jñānam is "consciousness", the term has a broader meaning of "knowing"; "becoming acquainted with", "knowledge about anything", "awareness", "higher knowledge".

Brahman:

Most interpretations state: "Prajñānam (noun) is Brahman (adjective)". Some translations give a reverse order, stating "Brahman is Prajñānam", specifically "Brahman (noun) is Prajñānam (adjective)": "The Ultimate Reality is wisdom (or consciousness)".

Sahu explains:

Prajnanam iti Brahman - wisdom is the soul/spirit. Prajnanam refers to the intuitive truth which can be verified/tested by reason. It is a higher function of the intellect that ascertains the Sat or Truth in the Sat-Chit-Ananda or truth-consciousness-bliss, i.e. the Brahman/Atman/Self/person [...] A truly wise person [...] is known as Prajna - who has attained Brahmanhood itself; thus, testifying to the Vedic Maha Vakya (great saying or words of wisdom): Prajnanam iti Brahman.

...
Wikipedia