Numbers is the third of five books called the Pentateuch. The others of course are Genesis, Exodus, Leviticus, and Deuteronomy. Numbers is a fulfillment of prophecy and the Abrahamic Covenant which was prophecy also. Numbers 1:2 Take ye the sum of all the congregation of the children of Israel, after their families, by the house of their fathers, with the number of their names, every male by their polls,
The children of Israel grew from a family and were now going to be a nation. They would be a nation of God's children. God brought them out of bondage and was bringing them back to the land.
Numbers becomes a mixture of laws and history of this becoming. This of course was under the leadership of Moses and the priesthood through the Levites. There was much more to learn and to grow. There are successes and failures here and we are given this history, warts and all.We see the principles of law given for this nation to represent God as the children of God.