You just need to read https://www.irs.gov/newsroom/helpful-facts-to-know-about-capital-gains-and-losses as that seems to put it into more of a plain language easier to understand.
It states The maximum tax rate on a net capital gain is 20 percent, but for most taxpayers a zero percent or 15 percent rate will apply. In addition, capital gains may be subject to the net investment income tax of 3.8 percent when income is above certain amounts.
There's other information that will apply to you also.
