"All the number ... is one hundred and eighty-six thousand four hundred." This number includes all of the men in the tribes that camped under the standard of Judah. AT: "The number of the men camped under the standard of Judah is 186,400" (See: [[rc://en/ta/man/translate/translate-numbers]] and [[rc://en/ta/man/translate/figs-explicit]])
This means that when the Israelite camp moves, the three tribes that camp east of the tent of meeting will start walking out before the other tribes do. AT: "When travelling, they will start walking first" or "When the Israelites leave, those tribes will leave first" (See: [[rc://en/ta/man/translate/translate-ordinal]] and [[rc://en/ta/man/translate/figs-explicit]])