Presumption of guilt means that someone is assumed to be guilty of a crime until they can prove that they are not. This means that when someone is accused of a crime, they have to prove that they didn't do it instead of the other way around, where they are seen as innocent until proven guilty. Think of it like your mom telling you that you ate the last cookie without leaving any for your brother - you have to prove to her that you didn't instead of her having to prove that you did.