Reddit reviews Erfolgreiche Geldanlage für Dummies (German Edition)

The blog and podcasts from Listen Money Matters are a great introduction for someone new to investing. I´d start here: https://www.listenmoneymatters.com/investing-101/

Keep in mind that they write from a US standpoint. The basic ideas and principles are the same, but for specific tactics you´ll have to look for more localized information.

I´m a non-Spanish resident in Spain and this book was super helpful. Maybe there´s a similar edition available in Germany? (This one?)

And finally I´d also recommend reading A Random Walk Down Wall Street and/or The Intelligent Investor.

These 3 resources you should give you a good foundation to start your journey. From there you can find answers to specific questions on subs like this one /r/finanzen and /r/investing and Google searches.

Good luck!