A radio scanner is like a special gadget that lets you listen to different kinds of radios. It's like having a magic ear that can hear all the different radio frequencies around you.
Imagine that you have a bunch of radios around you, all playing different songs at the same time. But you only have two ears, so you can only listen to one song at a time.
That's where the radio scanner comes in! It can hear all the different songs at the same time, and you can use the scanner to switch between them easily.
But "radio frequencies" might sound like a fancy word. So let's explain it this way - you know how you can tune different channels on your TV to watch different shows? That's because each channel has a different frequency. Radios are kind of the same, they have different stations that transmit on different frequencies.
The radio scanner can pick up all those frequencies and let you listen in on whatever is happening, whether it's music or people talking. You can even find special frequencies that are used by the police or firefighters to communicate with each other.
So, in summary, a radio scanner is a special gadget that can listen to and tune into different radio frequencies, even if they're all happening at the same time.