Okay kiddo, so a long time ago, back in 1707, Scotland and England were two separate countries. They had their own governments and laws and everything. But then, some fancy important people came together and decided that it would be better if they joined forces and became one big country called Great Britain.
To do this, they created something called the Acts of Union. This was like a special set of rules that both Scotland and England agreed to follow so they could work together as one big country.
Some people in Scotland were worried about this because they thought they might lose some of their traditions and culture. But in the end, they agreed to it because they thought it would be better to be united with England than to fight against them.
So, the Acts of Union made Scotland and England come together and become one big country called Great Britain. And that's how it stayed for a long time until more recent times when some people started talking about changing it again. But that's a story for another day!