After all this, God announces that it's a pretty good time to take another census. Lots of people have died, so God's gotta get a better count of who's still left standing.
So, Moses tells everyone camping out on the plains of Moab that it's time to start counting again. Gather up all the men over twenty (by tribe, of course). Basically, we're looking for everyone who can go to war.
After a really long and detailed list of names, the total number of men counted is 601,730. Remember the first census had only 1,820 more people. That means the Israelites were pretty busy. For almost every single person who died in those crazy plagues and punishments, new babies replaced them.
God tells Moses to use this information to make sure that all the tribes get a fair share of the land.
Then, Moses goes and counts the Levites. Good news, guys—your ranks have increased in number. There's about 1,000 more Levites than there were forty years ago. Levites for the win!
At the end of all this counting, we're told that, aside from Moses, Eleazar, Caleb, and Joshua, no one who was counted in this census was counted in the first one. That whole older, sinful generation has died off (or been killed off). Now the new generation is ready to waltz into the Promised Land just like God, well, promised.