Interlingue is a way for people from different countries who speak different languages to communicate with each other. It's like a secret code that everyone agrees to use, so they can understand each other without having to learn each other's actual languages.
Think of it like this: imagine you want to talk to your friend who speaks a different language, but you both know a third language that you both learned. That third language is like interlingue - a way to communicate even though you speak different languages.
Interlingue has its own set of vocabulary and grammar rules that are easy to learn, and it's meant to be a fair way for people to communicate without one language being more important than another.