"What do we learn from conflict?"
This a very broad question and can be answered in many different ways. Let me give you a few perspectives.
First, a person might learn that conflict is not worth it. Conflict could be costly, time consuming, and most of all destructive.
Second, others might learn the opposite lesson. If a person or nation is fighting for what is right and noble in the face of evil, then conflict might be a sign of courage. In this sense, there is no price that is too high. Even if you lose, you might have to fight.
Third, there are many other lessons a person can learn through conflict, like it is hard, requires sacrifice, and is costly in many different ways. In short, wise people will learn much from conflict.