If your company is publicly traded, learn about the variety of SEC filings that most C-level executives are responsible for. In particular, learn how to parse the footnotes of 10K/S1 filings — an income statement might be 1-2 pages but the footnotes are often 30+ pages. The interesting choices a company makes are often in the footnotes. For example, the related party transaction for WeWork’s “We” trademark that everyone was up in arms about appears on page 199 of the filing.
Finance is about cashflows. GAAP accounting is about subjectively spreading costs across periods. The two are often at odds. Learning to navigate both and knowing which your audience cares about is critical. You often need years of context about a business to be able to make contributions on this front.