The "scepter" and the "staff" are long decorated sticks that kings carried. Here they refer to the power to rule. And, "Judah" refer to his descendants. Alternate translation: "The power to rule will always be with the descendants of Judah" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Possible meanings are 1) "until the ruler comes to Shiloh. Then the nations will obey him" or 2) "until the nations obey him and bring him tribute." Many people consider this a prophecy about the Messiah who is a descendant of King David. David is a descendant of Judah.