Molecular orbitals are like playgrounds for atoms. Instead of having separate places to play, two or more atoms share the same playground. This happens when two or more atoms come close together and their electrons start to mix and play together.
Just like how you can mix different colors of paint to create a new color, different electrons can mix to create new "playgrounds" that the atoms all share together. These new playgrounds are called molecular orbitals.
When electrons mix together to form a molecular orbital, they end up spreading out over the whole group of atoms instead of just staying close to their original atom. This makes the group of atoms act like a new "super-atom" with its own unique properties.
Molecular orbitals are important to understand because they help us explain how chemical reactions happen. When two or more atoms come together, the way their electrons mix and share playgrounds can determine whether or not a reaction will happen.