Sheets provide a way of structuring your ideas and purposes for your app. When you create an empty app, it is good practice to first build a structure of empty sheets, where each sheet represents an idea or a goal. This will give you, and others who you will share your app with, a good overview of the app.
For example, let us say that you want an overview of your business's key metrics, an analysis of revenues, and a way to show how each sector and salesperson is performing each month, quarter, and year. Instead of having all this information in one place, you could structure it by having one sheet for the key metrics, one for the revenues, and one for the performances.
This section describes how you can create and modify sheets, add descriptions, change the properties of sheets, and much more.