Om is a Sanskrit word, a solemn statement found at the beginning of much Indian religious literature.
The Om symbol is the most sacred Hindu mantra, and, according to the Hindu scriptures, represents the synthesis and the essence of all mantras, prayers, rituals, sacred texts, celestial beings or aspects of the Divine.
By uttering the sound “ah uh mmmm”, as it is used in mantras, you are imitating the harmonic tone of all creation.