To call something after something else is an idiom that means to give it the same name or a similar name. Alternate translation: "They called these days Purim, like the word Pur" (See: [[rc://en/ta/man/jit/figs-idiom]])
This is the name of the festival that commemorates the salvation of the Jewish people in ancient Persia from Haman's plot to destroy and kill all the Jews in a single day. (See: [[rc://en/ta/man/jit/translate-names]])