Here are some very basic resources for true beginners to investing. I recommend picking 1 or 2 very simple intro investing books, and 1 or 2 behavioral/psychology books. Look things up on investopedia.com if there are terms or concepts you don't understand.
Read a lot, but make sure you pause to absorb, reflect, write, and discuss with friends! Ask why, and write down a list of questions or things you want to understand.
Books for basic investing concepts
Books for basic behavioral finance concepts
Books/resources for basic accounting and finance concepts
Basic investing/finance/valuation training
NYU Stern Professor Aswath Damodoran has open-sourced a huge amount of material from the classes he teaches on introductory investing, finance, and valuation. You can find them at the links below. Some of the classes can be taken for certificate credit, for fee; others are completely free.
Learn from business titans
Founders Podcast - every week host David Senra reads a biography of a great entrepreneur, businessperson, or historical figure and walks you through his key takeaways. It's an awesome, fast way to learn from the titans of history. (Don't let this stop you reading some full-length biographies too!)
The Art of Investing "Podclass"
Paul Buser and Rick Buhrman of Sator Grove Holdings have taught, for years, a class at Notre Dame called the Art of Investing. For the first time, in 2023, they have created a "podclass" following the guest speakers and learnings from the course. I highly recommend giving it a listen. Learn more here.