“Om ma ni pad me hum” is the Sanskrit mantra associated with the four-armed Avalokiteshvara, whom is also called Chenrezig in Tibetan, and “Guan Yin” in chinese. Please view the first Icon at section “Lords of The Three Enlightened Families” of Tibetan Buddhism Iconographic Guide.
“Om” is to be found in Indian religions.
“Ma ni” means “jewel” or “bead”
“Pad me” means the “lotus flower”, the Buddhist sacred flower,
“Hum” means the spirit of enlightenment.
Tibetan Buddhists believe that saying the mantra “Om Ma ni Pad me Hum” out loud or silently to oneself will invoke the powerful benevolent attention and blessings of Chenrezig, the embodiment of compassion.
In use, this 6 words are commonly carved onto rocks or written on paper which is inserted into “Prayer Wheels”, which effects the same as reciting the mantra as many times as when an individual spins the wheel.