Well little one, Joseph Freeman was a man who lived a long time ago and was part of a religious group called the Mormons. They believed in following a special book called the Book of Mormon that they believed was a message from God.
Joseph Freeman was actually not a real person, but it sounds like you might mean Joseph Smith? He was the founder of the Mormon church and believed he had a special connection to God. He said that an angel came to him and told him about some golden plates that had a special message that God wanted him to share with the world.
Joseph Smith said he used special glasses to read the message on the plates and then he wrote it down in a book that became known as the Book of Mormon. He and his followers started a new religion based on the teachings in that book.
Nowadays, there are still many people who follow the Mormon faith and believe in the messages that Joseph Smith shared with the world. They have temples and churches where they go to pray and learn more about their beliefs.