Alma shows us how best to work with those that don't believe the way we do or who aren't acting the way they should. Be Humble and Helpful or Scornful and Contentious. A powerful chapter for self reflection.
The Amlicites have separated themselves from the Nephites and we learn a little bit about the division of those that choose to follow Christ and those that choose a different path.
Amlici doesn't get his way and chooses to bring contention into life. We learn a bit about contention and how to try and avoid it.
Nehor teaches priest craft and we learn about the economy of being a follower of Christ.
Mosiah changes the entire leadership structure of the Nephites and Alma the Younger takes over leadership. We learn 2 important leadership lessons from Mosiah in the process.