Trading 212 is essentially a gambling app.
They make money off you on the bid offer spread ie the price difference between what they’ll buy shares off you at, and what they’ll sell them to you for.
The more you trade the more money they make, which means the more you lose. For example I’ve lost ~0.5% interest this month by restructuring my portfolio.
If you are very disciplined it can be a cost effective method of investing.
Depending on your age, appetite for risk and investing goal you would probably be best off in a Vanguard Life Strategy fund to start with – either your retirement date if you want true fire and forget, or one of their XX:XX split funds if you want to be more involved and know a bit more about what you’re doing and your risk appetite.
More involved than that and I’d recommend you start reading up on passive investing and portfolio theory.
Do not buy individual shares.
Do not day trade.
If you’re trading in shares, and don’t know who’s getting screwed over by your trade, then it’s you getting screwed.