The "land of Judah" and "Egypt" refer to the people in those places. The Egyptians will stagger because they are afraid. Alternate translation: "The people of Judah will cause the Egyptians to stagger" or "The people of Judah will cause the Egyptians to be terribly afraid" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Here, "them" and "they" refer to the Egyptians and "her" refers to the people of Judah. Alternate translation: "Whenever anyone reminds the Egyptians of the people of Judah, the Egyptians will be afraid"