The word Hamsa originates from the ancient Semitic root word for the number five.
The number five is considered to have special spiritual power of protection. We
know from the Holy Kabbalah that there are ten Sephirot (spiritual dimensions)
from which the universe was created by The Creator. The fifth Sephirah is Gevurah
(power or strength) which manifests itself in our world as the forces of nature
and in the human realm justice or judgment. We perceive nature with five senses.
The Torah is divided into the Five Books of Moses. The fifth letter in the Hebrew
alphabet is Heh which represents one of G-d's holy names. All these associations
with the number five, of course, correspond to the five fingers of the Hamsa hand.