This is exaggerated to emphasize the seriousness of the event. There were still some animals alive that were afflicted by later plagues. However, it may be best to translate this with the word "All." (See: [[rc://en/ta/man/translate/figs-hyperbole]])
Here "Egypt" refers to the people of Egypt. Alternate translation: "the cattle belonging to the people of Egypt" (See: [[rc://en/ta/man/translate/figs-metonymy]])