"Madonna and Child" is a painting or sculpture that shows a woman, who we call Madonna, holding a baby in her arms. Madonna is actually Mary, the mother of Jesus, and the baby is Jesus as a young child.
These artworks were created by many artists throughout history to show the love and bond between Mary and Jesus. They are very important to people who are Christian, because they believe that Jesus is the son of God and Mary is his mother.
So, when you see a "Madonna and Child" artwork, you are looking at a special moment between a mother and her child, who Christians believe is the son of God.