Welcome back, mazenjaber.
Location tracking shows the different stores while the Class tracks the different departments within the store. Depending on your business needs, you can either use Class, Location, or both.
For additional information about how classes and locations work in QBO, check out this article: Using Classes and Locations in QuickBooks Online.
The good thing with using the location as a tracker is that you can filter the Accounts receivable aging summary, Accounts receivable aging detail, and Open Invoices reports by location.
You might also want to visit our QuickBooks Online learning guides for tutorials and webinars about the product.
Be sure to get back to me if you have additional queries. I'll be around to answer them for you. Have a good one.