Matthew 28:19 is a verse in the Bible that tells us what Jesus said to his disciples before he left them to go to heaven. Jesus said, "Go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit."
This means that Jesus wanted his friends to tell everyone they meet about him, and try to teach them how to be like him. He also wanted them to baptize people, which means to sprinkle them with water or dip them in water as a symbol of their decision to follow Jesus.
Jesus said they should do this in the name of the Father, who is God, and the Son, who is Jesus, and the Holy Spirit, which is God's helper that helps people understand and live like Jesus.
This verse is important to Christians because it tells them that they should share the good news about Jesus with others and help them become followers of Jesus, just like the disciples did after Jesus left.