Okay kiddo, so you know when you invent something really cool like a toy or a machine? Well, that's called an invention and you want to make sure no one else copies it or steals your idea. That's where patents come in.
A patent is like a special paper that the government gives you that says you are the only one who can use your invention for a certain period of time. That means other people can't make the same thing as you and they can't sell it either.
Now, the Substantive Patent Law Treaty (SPLT) is like an agreement between lots of different countries. They all promise to follow the same rules when it comes to patents. That means if you make an invention in one country, you can get a patent in another country too without having to do everything all over again.
It's like having a big group of friends who all agree to play by the same rules in a game. That way, everyone knows what to do and it's fair for everyone. The SPLT helps inventors all around the world protect their ideas and make sure no one else copies them.