Evangelii Nuntiandi is a fancy name for a big letter that a very important man called Pope Paul VI wrote a long time ago. The letter talks about how important it is for special people called Christians to tell other people about a really amazing person called Jesus Christ.
You see, Jesus was not just any ordinary person. He was really special and taught us many things, like how to love and help others. So, Pope Paul VI wrote this letter to make sure that all Christians knew that it was their job to share this message with everyone they meet.
In the letter, Pope Paul VI also explained different ways that Christians can share the message of Jesus with others, like talking to them or showing them how to live like Jesus did. He also talked about how important it is to show love and kindness to people, even if they don't believe the same things as us.
So, in a nutshell, Evangelii Nuntiandi is just a fancy name for a letter that reminds us that it's really important to share the message of Jesus with others and to show love and kindness to everyone we meet.