Redemption
The Israelites learn about redemption when God takes the Levites in place of their firstborn sons. He is pointing them to the future redemption that will be offered through Jesus for all mankind. Through the Israelites, we learn what redemption looks like which gives us a fuller appreciation of the price that Jesus paid for our lives.
The Israelites also take their first census, & since they are about to begin their journey to the Promised Land, they get their camping and travel arrangements. The Levites are also given their specific duties regarding the Tabernacle. We too have been redeemed for His service. Because of His redemption, we have a desire to live for Him.