While the exact meaning and significance of the prayer wheel are multiple, Alvin Hunter states

three interpretations in his article "Tibetan Prayer Wheels."  First he says that the prayer wheel is

loosely based upon the Indian Buddhist phrase 'to turn the wheel of the law,' describing the

spreading of the teachings of the Buddha, thus the prayer wheel is the spiritual wheel made

concrete. Next Hunter suggests that the contiguous unbroken spin of the wheel is a visual

declaration that Buddhist teachings offer a complete circle of inspirational knowledge.  Hunter's

final interpretation is that the prayer wheel is the physical symbol of the endlessly flowing cycle of

birth and rebirth.