Okay kiddo, imagine you want to bake some cookies all by yourself. You have to do everything by yourself, like getting the ingredients, mixing them up, and then baking them in the oven. But, that's a lot of work for just one person, right?
Now imagine if your friends or family members wanted to help you, but they can only do one thing each. One person can get the ingredients, another person can mix them up, and the last person can keep an eye on the cookies in the oven.
This is what we call the indivisibility of labor. It means that some tasks are too big or too complicated for one person to do by themselves, but if they work together and each person does one specific task, then they can complete the task more efficiently.
This is how many businesses and industries work too. Each person has a specific job or task to do, and they work together to make the whole process run smoothly. So, just like how your cookie baking becomes easier with the help of your friends and family, jobs and businesses become easier when people work together and specialize in specific tasks.