Okay, kiddo, let me explain it in a way that even a five-year-old will understand. Mary, the mother of Jesus, is a special lady for Catholics. Catholics believe that she is very close to God because she gave birth to Jesus. Many people pray to her and ask her to help them.
Devotions to Mary are special ways of showing her our love and asking for her help. Catholics do things like praying the Rosary, or saying special prayers called novenas, or visiting her statues or shrines. These things help them feel closer to Mary and to God, and they believe that Mary hears their prayers and intercedes for them with God.
It's like having a really powerful friend who can talk to Jesus for you and ask Him for help when you need it. So when you're sad, scared, or need something, praying to Mary can make you feel better because you know she's always there for you.