What does Numbers 31:19 mean?

And encamp ye without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify yourselves on the third day and on the seventh day, ye and your captives.

And do ye abide without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify both yourselves and your captives on the third day, and on the seventh day.

And encamp ye without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify yourselves on the third day and on the seventh day, ye and your captives.

You yourselves will have to keep outside the tent-circle for seven days, anyone of you who has put any person to death or come near a dead body; and on the third day and on the seventh day make yourselves and your prisoners clean.

`And ye, encamp ye at the outside of the camp seven days--any who hath slain a person, and any who hath come against a pierced one, ye cleanse yourselves on the third day, and on the seventh day--ye and your captives;

And stay without the camp seven days. He that hath killed a man, or touched one that is killed, shall be purified the third day and the seventh day.

And encamp outside the camp seven days; whoever hath killed a person, and whoever hath touched any slain; ye shall purify yourselves on the third day, and on the seventh day, you and your captives.