The "Seven Joys of the Virgin" is a special thing that people who believe in God do to remember the happy moments in the life of Mary, the mother of Jesus.
When Mary was told she was going to have a baby, that was the first joy. It made her very happy because she was going to be a mom.
The second joy was when Mary visited her cousin, Elizabeth, who was also going to have a baby. When Mary got there, Elizabeth's baby jumped in her belly because he knew Mary's baby was very special. That made Mary very happy too.
The third joy was when Mary gave birth to Jesus. She was so proud to be his mom and to hold him in her arms.
The fourth joy was when three wise men came to visit Jesus and bring him gifts. Mary was happy that other people could see how special her baby was.
The fifth joy was when Jesus was found in the temple. Mary and Joseph had lost him for a bit, but they found him talking with the wise men and Mary was relieved and happy.
The sixth joy was when Jesus performed his first miracle. He turned water into wine at a wedding and Mary was so proud of him.
And finally, the seventh joy was when Mary was taken up into heaven to be with Jesus. This was the last time she saw him and it made her very happy to be with him again.
So, when people talk about the "Seven Joys of the Virgin", they are remembering all these happy moments in Mary's life with Jesus.