If you want to read more about Index funds(Mutual fund & ETFs), you might find this helpful: https://www.bogleheads.org/wiki/Index_fund
- https://www.whitecoatinvestor.com/ - targeted mostly at doctors and other high earners but can be useful
- https://old.reddit.com/r/financialindependence/ - subreddit about achieving financial independence and retiring early. It's a bit boring but the financial advice is pretty sound and never really changes. You can probably just read the sidebar or skim when you're bored.
Once you read the "Getting Started" and "Index Funds" on bogleheads, I'd suggest https://www.bogleheads.org/wiki/Three-fund_portfolio . It shouldn't take long, and by that point you should at least be able to understand enough to set up your investment accounts with some confidence.