It is the philosophy and foundation for magical societies. It draws on the Egyptian and Jewish Kabbalah.
It is not used for the same purpose of Jewish Kabbalah. Though many mistakenly think it's the same, it isn't
Hermetic = greek, Kabbalah = secret knoweledge. This is a blend of Judasim and the Greek mystery schools that thrived in the near middle east and egypt in the early 1st and 2nd centuries AD.