Something is distributed when it's divided up or spread around, the way cupcakes might be distributed among guests at a birthday party.
Distributed is a word that's often used to describe the stuff that businesses sell. When a truck pulls up to a convenience store and the driver unloads cases of soda, the soda is being distributed. The driver will go from store to store, distributing all of the soda in the truck between different stores and restaurants. Words and ideas can be distributed too, which is what happens at school when students are lucky.
