Imagine a big playground where you and your friends usually play. The playground has a fence around it to keep everyone inside. Now, imagine that the playground is like a country, and the fence around it is like a border.
A border town is a place right next to this fence or border. It's like a special part of the playground that's right next to the fence. Sometimes, people who live in one country might go to the border town just to see what the other country looks like, or to buy things that are only sold there.
Since the border town is so close to the fence, there might be special rules for people who live or visit there. The rules are like instructions on how to behave so that everyone can stay safe and happy. These rules might say things like "Don't cross the fence without permission" or "Don't buy anything illegal or dangerous."
So, a border town is like a special place that's right next to the border of a country. It might have special rules, and people might go there to see or buy things that are different from what they have in their own country.