The Qabalah is a Judaic school of thought that discusses God's relationship between Himself and the universe (including man) that he created. The Sephirot is the diagram that presents the ten different emanations of the Qabalah. It is actually the diagram that is behind Msyu's back when Kimimaro sold one stock of his asset to Mikuni.
When people on /a/ were joking about the stock being sold as Msyu's vagina, they weren't wrong in that sense: it was located in the Kingdom, or the Malkuth. More details about the Malkuth and expounded pictures can be seen here.