I might ask a librarian for good books on it. Investopedia can also help break things down.
My personal, unsolicited advice (edit: this is US-based advice, I'm not familiar with EU regs): I personally prefer low to medium risk stuff like the S&P 500 index funds and mutual funds. Max your 401k if your company matches it. Dump that into an IRA whenever you switch jobs. HSAs are a pretty decent deal if you live in the US and your company offers one.
Mostly, it's about saving and investing whatever you have, and not spending all of your money. You don't need to be a genius on this stuff. Lower risk investments + time = good outcomes. As you get higher paying jobs, keep investing more and more into your retirement and investment accounts.