Gert-Jan Tamerus is a person's name. It's like saying David or Emily. People have names to help us recognize and remember who they are.
Like every other person, Gert-Jan Tamerus has his own story. He has his own family and friends, and he does different things in his life, just like you do things in your life too.
Sometimes people become famous or get in the news for something they did, and it helps more people know about them. But the important thing to remember is that everyone is unique and has their own story to tell.