Ask HN: How to save/invest/deal with money?

I am a junior developer working at my first job as a software engineer. I'm studying in a part time model so I am studying 50% and working 50% of my time. I get my salary every month but... What should I do with the money? I am still living with my parents so I do not have to cover living costs, only pay them a little bit of rent. I never buy anything and I spend all my free time studying which I like. I have nearly 0 expenses. So I thought maybe it would be good to invest this "extra income" coming in every month. But where do I start? I know nothing about finance or economy and whenever I try to look into it I don't even understand how to get started because the entry fees seem high. I am in Europe, maybe that's relevant. I feel this money from my job is only a burden for me because all I do is have to pay the account fee to my bank... Highly appreciate any advice!