Bro if you don't know the slightest about trading you should be looking into that before even trading, let alone day trading. If you have a stock (or if you're buying doge/crypto it's called coin not stock) and if you sell any coins you buy and have them less than one year that's called a short term capital gain. They tax you in the same bracket you would be regularly if you worked a 9-5. Google 2021 tax brackets/capital gains tax and you'll be able to see what bracket. It's around 40-82k for the 22% bracket. Yes robinhood will send you a tax form. One more thing, just know that robinhood is shady af with crypto and the coins you guy you technically don't own them.