Do you know what a radio is? It's like a special box that can send and receive sound waves through the air, so people can talk to each other from far away places.
Well, the geo-mobile radio interface is a way for radios in different parts of the world to talk to each other.
Think of it like a special language that radios use so they can all understand each other, like when you learn how to speak a different language in school or when you talk to people who speak another language.
The "geo-" part means that it has to do with location, or where you are in the world. So if a radio in one country wants to talk to a radio in another country, they use this special "geo-mobile" language so they can understand each other, even if they are far apart from each other.
It's a really important thing to have, especially for people who work in emergency services like police officers, firefighters, or doctors. They need to be able to talk to each other no matter where they are in the world, so they can help people who are in trouble.