Alright kiddo, so a 'border blaster' is basically a really powerful radio station that broadcasts its signal across borders. Imagine you want to yell really loudly across a large room, but instead of yelling, you use a radio that can be heard far away.
Now, some countries have rules about how powerful a radio station can be, so they don't interfere with other signals. But border blasters often operate in places where these rules are not as strict, and can broadcast much farther than normal. So instead of just being heard in one city or town, a border blaster can be heard in multiple cities and even other countries!
However, because border blasters are so powerful, they can also interfere with other radio signals that might be trying to use the same frequency. So while they can be really fun to listen to and offer a lot of variety in music and programming, they also have to be careful not to cause problems for other people trying to use the airwaves.