The total number of male Levites one month old or older was 23,000. But these men were not counted with the other Israelites, because they were not given any of the land among the other Israelites.
Moses and Aaron the priest had counted the Israelites in the Desert of Sinai, but no one Moses counted on the plains of Moab was in the first counting.
The Israelites had moved about in the desert for forty years. During that time all the fighting men who had left Egypt had died because they had not obeyed the Lord. So the Lord swore they would not see the land he had promised their ancestors to give them, a fertile land.