The onramp for finance is accounting. There is no other right answer. This is also essential for general business administration. Accounting is a huge topic; being able to read financial statements is a good, first tangible exercise. Best book I have found for this is Thomas Ittelson, Financial Statements. Using double-entry accounting methods for your own financials with a tool like Beancount is super helpful from a…
I would like to strongly second your recommendations regarding accounting. Double entry accounting is the root of all finance. If you understand it well enough to keep accurate accounts of your personal finances (credit cards, 401k, salary, pre/post-tax expenses, etc), you understand it well enough to fumble through a financial statement. I’d plug GNU Ledger, but really any double entry accounting software is good to…
I think at least a 100-level knowledge of account is beneficial to nearly every developer. Bookkeeping is, arguably, one of the oldest and longest-practiced "data processing" disciplines. It seems arbitrary and somewhat old-fashioned until you grok the reasoning and history behind it (double-entry sourced from summaries of various different "journals" to facilitate separation of duties, closing periods and rolling-up detail entries into totals because human computational power is limited, an equation that balances implicitly when there aren't entry errors, etc.)
From a personal finance perspective I think everyone should get some training in account but, sadly, that's probably way too optimistic of an attitude.