The Triskele can be seen all across the Celtic lands with it's most famous representations being found on the Newgrange kerbstones. There are varying interpretations of its meaning; life/death/rebirth, the three realms of earth/sea/sky, the three worlds spiritual/physical/celestial, the interpretations stretch on and on.
Here it is seen with the images of Maiden/Mother/Crone the phases of the life of the goddess, or the life cycle of the feminine.
It is a truly beautiful piece that inspires thought and reflection, what does it mean to you? That't the beauty of the piece, it is truly up to you to decide.