Just keeping track of cash that goes in and out of a business doesn't always reflect what's going on. This tutorial compares cash and accrual accounting. Very valuable if you ever plan on starting or investing in any type of business (you might also discover a nascent passion for accounting)!
Corporations use three financial statements to report what's going on: balance sheets, cash flow statements and income statements. They can be derived from each other and each give a valuable lens on the operations and condition of a business.
After you know the basics of accrual accounting (available in another tutorial), this tutorial will give you tools you need to responsibly understand any business.
How do you account for things that get "used up" or a cost that should be spread over time. This tutorial has your answer. Depreciation and amortization might sound fancy, but you'll hopefully find them to be quite understandable.