Hello Experienced Stock investors,

How is the gain or loss on stocks affect income tax?

Did you buy and sell stock? How did you do it?
If you are capable of buying and selling stock , by now you should have figure it out it's impact on income tax.
Here is the link.
https://www.irs.gov/instructions/i1040sd/ch01.html#d0e789

Just started via Robinhood

You can directly import tax document(capital gain loss/dividend) in turbotax from the major brokerage accounts including Robinhood.

There are two types of taxes on gains.. Long Term, which is for stock held for more than a year, and Short term is shorter than that.. The Long term are not taxed or taxed 15% depending on your income. Short Term are taxed as just your regular income. However Loss offsets the Gain which is a good thing here in US.