Negros killings is a very upsetting and sad topic. It's about people who have been hurt or killed just because of the color of their skin, especially people with dark skin who are often called "Negros".
You know how you have friends who might look different than you, but you still play and have fun together? Well, some grown-ups sadly don't like it or understand that people can be different and still be friends. They might get angry and hurt people who are different than them, just because they don't look the same or have the same skin color.
This is very wrong and it makes a lot of people sad and upset. Many people are working to make people understand that being different is okay, and that everybody deserves respect and kindness no matter what they look like.