Without more detailed information, we can't specifically identify what your capital gain is caused by, but when you sell something at a gain, you typically will have a capital gain. This can be from stocks, personal items, a home, or more.
No one can see your screen or your tax return so we cannot guess why you have capital gains. There are a variety of possible reasons. Provide some details about what kinds of income you have entered.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**