Okay, so here's the thing: people don't always behave nicely toward each other. Sometimes, they hurt each other or do wrong things. When this happens, the person who was hurt or wronged might feel really angry and want revenge. Revenge means getting back at someone for what they did to you.
Now, blood vengeance is when someone is killed, usually by someone else, and their family or friends feel like they need to take revenge on the person who killed them. It's called "blood" vengeance because the person who was killed was related to the people who want revenge by their blood, or family ties.
People who believe in blood vengeance often think that it's important to show that they won't tolerate people hurting their family or friends. They might feel like they need to take revenge so that no one else will hurt them again. This can lead to a cycle of violence, though, where one act of revenge leads to more and more violence.
The idea of blood vengeance has been around for a very long time, but most people now think it's not a good way to solve problems. Instead, they try to use the law and the justice system to help resolve conflicts and punish people who do wrong things.