People who have not started investing in the stock market are often scared to invest as they do not know how the stock market works and think all their money will be lost if they start to invest!
Using Trading 212 app you can start practicing using virtual 50000 Euros. You can invest in many individual stocks and ETFs using the virtual money and see how the stock market works, how real life events affect the stock market and create your confidence. After you are confident, then you can open a brokerage account and start using actual money.
As Trading 212 is a UK based company, I would not recommend using it if you are in Germany. Instead I would recommend Trade Republic or Comdirect.
You can watch my videos on those topics here:
*None of this is meant to be considered as investment advice, as I am not a financial expert and am only sharing my experience with stock investing. The video and article are accurate as of the posting date but may not be accurate in the future.