This is the name and description of Haman, one of the king's officials. See how you translated this in [Esther 3:1](../03/01.md). (See: [[rc://en/ta/man/translate/translate-names]])
Why he threw Pur, or lots, can be stated clearly. AT: "he threw Pur (that is, he threw lots) to find out what would be the best day to attack the Jews" (See: [[rc://en/ta/man/translate/figs-explicit]])
"Come back on his own head" means that it should be done to Haman. AT: "the wicked plan Haman developed against the Jews should be done to him" (See: [[rc://en/ta/man/translate/figs-idiom]])