-Sigh- You don't have to own a business to have capital gains.
Capital gains. That's profits from the sale of real estate, stocks, bonds, or some other asset. Apparently, she sold something (or somethings) for less than she paid, so she had a loss.
The significance here is that she (along with Bill - they file jointly) PAID $3.6 million in 2015, and their joint effective tax rate was 43.2%. Since 2007, they've paid $43 million in income taxes.
So they pay their taxes, whereas Trump appears to be hiding his returns to avoid absolute confirmation that he doesn't pay any.
Once again, you're comparing apples to orange.
The tax returns from 2007 through 2015 are available for both Clinton AND Kaine are available online right this second - because they have nothing to hide in them.
Trumps? Exactly.