"learn business" was mentioned but there seems to be a lot discussion here around accounting and finance - those aren't "business", at least not the core of it anyway.
Accounting for one is recording what has already happened in a business - its merely reporting, nothing more. Its a reporting function of business.
There is far too much focus I feel on accounting and finance in MBA courses. Its not business. An MBA degree these days is sort of an entry price or piece of paper into the C-suite. I don't see that MBA degrees actually teach a lot of business.
Business is finding people and having them pay for value - a product or service. If you have an accounting department or knowledge of accounting/finance, you don't have a business, you have reporting. That's all you have.
Business is far more about sales, marketing, pricing, psychology, product/market fit. Then there is the delivery of that value - the actual product or service.
I'd also say a big part of business is learning about and being about to solve problems in a certain market.
Accounting/finance in a discussion of "learn business" should come way down the list IMO - its nothing more than reporting.
(A lot of the resources here focusing on accounting or finance are great resources - if you want to learn accounting / finance or if you want to get an MBA but they don't necessarily equate to learning "business". Also there is no better way learn business than doing rather than reading about it. I heard someone once say that you'd learn more about business running a lemonade stand than doing an MBA - I tend to agree).