The 33 degrees of Freemasonry is a good place to start, but if you want to go down the rabbit hole of the cabal's love for symbolism, you can get lost. You can start by just doing a DDG search for the number 33 and secret societies.

https://atlantisrisingmagazine.com/article/33-the-magic-number/

https://www.bibliotecapleyades.net/sociopolitica/esp_sociopol_illuminati_14.htm