John 16 is a chapter in a book called the Bible which talks about Jesus and his friends. In this chapter, Jesus tells his friends that he will have to leave them soon and go back to a place called heaven.
But Jesus promises that he will send a helper called the Holy Spirit to be with his friends always. The Holy Spirit is like a special power that helps people understand and follow what Jesus taught them.
Jesus also says that his friends will face some difficulties and troubles when he is gone, but they should not be afraid because he has overcome the world. This means that Jesus is bigger and stronger than any problem or bad thing that can happen.
Overall, in John 16, Jesus is comforting his friends and giving them hope for the future by letting them know that they will not be alone and that he will always be with them in spirit.