from twenty years old and upward, all that are able to go forth to war in Israel, thou and Aaron shall number them by their hosts.

You and Aaron are to number those who are twenty years of age or older by their divisions—everyone who can serve in Israel’s army.

from a son of twenty years and upward, every one going out to the host in Israel, ye do number them by their hosts, thou and Aaron;

from twenty years and upward, all that go forth to military service in Israel: ye shall number them according to their hosts, thou and Aaron.