Okay, so let's pretend you and I are playing with toy cars. We're going to make a pretend town with our toy cars. You can have your red cars and I'll have my blue ones.
Now, let's say we want to make a special area in our pretend town just for making and selling things - like toys, clothes, and food. We call this special area an "industrial district."
In our industrial district, there are big buildings where people work to make products. There might be factories there where they make toys and clothes in really big quantities.
Once they make the toys and clothes, they can sell them to other stores or people who want to buy them. There might also be stores in the industrial district where they sell the things they make.
It's like a special part of our pretend town where people make and sell things all in one place. In real life, industrial districts are like that, too - they are special areas where businesses make things and sell them.