This is the Sanskrit symbol for Om, the primeval sound of the universe, the basic resonance from which all else comes. Om is in every place, mind, and heart.
Often spelled Aum, it is usually spoken almost under the breath and pronounced in the consciousness as well as in the mouth as “Omm….”
The small silence at the end is as important as the sound itself.
It is said that the recitation of Om while contemplating the mystical symbol helps to calm even the roaring waves.