The free share of stock from Robinhood is not reportable until sale of the stock.
If you were given the stock in 2020 with a value of $5 and sold the stock in 2021 for $15, you would report a $10 capital gain on form 1040 Schedule D.
If you owned the stock more than one year, you would qualify for long term capital gain treatment. If you owned the stock less than one year, you would qualify for short term capital gain treatment.
Robinhood would provide a 1099-B broker statement for the sale transaction.
See also this.