Ok kiddo, so back in 1975 some really smart people got together and made a plan for how all the different countries in Europe can use the radio waves to talk to each other without causing any interference. They called it the Geneva Frequency Plan.
Think of it like a big playground where lots of kids want to play with different toys at the same time. But if everyone plays with their toys too loudly, it can be really hard to hear what someone else is saying. That's kind of what would happen if all the countries tried to use the same radio waves to talk to each other without a plan.
So this plan said that each country gets their own designated space to play in. And they have to use certain frequencies, or parts of the radio waves, to talk to each other. This way they can all play without causing problems for each other.
It's kind of like if you and your friends decided to use different parts of the playground to play different games. You might play tag in one area and they might play soccer in another area. But you agree to use certain rules for each game so everyone can have fun without getting hurt or causing problems.
Overall, this plan helped make sure that all the different countries in Europe could talk to each other over the radio waves without causing any interference. It was like a big agreement to use certain parts of the playground and follow certain rules.