This is The Key of Solomon Tetragramaton Alpha Omega, a sigil connected with Enochian systems of
magic. In Christian belief, Christ was the "Alpha and Omega" (the
beginning and the end), "Otheos" is a reference to God, and the
phrase "Eheyeh Asher Eheyeh" (also from the Bible) means "I am
who I am".
Enochian: Refers to the times of Enoch, it refers to the language that both angels and humans had before the tower of Babel. This protection symbol refers to those times. It contains the Tetragramaton in the center and around it the inscription "I Am He Who I Am, The Alpha and The Omega."
Tetragramaton: This is one of the strongest protection amulets that exist. Another of its qualities is to show the wearer the path to inner light and wisdom. If the star is upside down, it represents the masters of light, while upside down, with the two points facing up, it represents darkness.
Alpha and omega: The beginning and the end.
Otheos: reference to God.
Phrase "eheyeh asher eheyeh" (also from the Bible) means "I am who I am."