And as you point out under Hillary's watch the State Department "lost" $6 billion it cannot account for! This is a great counter-attack and I hope Trump takes this up either in the debates or in ads or both. She lost $6 billion of your money, and now she asking for $1 trillion more! Nuts!
An example: you borrow $100,000 to invest in something. The investment goes sour, and you lose all of it. You have a net loss that year, but you still have to pay back the $100,000 loan.
However, the truth is that carrying forward a loss simply allows you to offset future gains. For example, you buy a stock for $10,000 and sell it for $5,000. That's a $5,000 loss. If you have other capital gains in the same year, that $5,000 is subtracted from those.
On your individual return, you can offset $3,000 of ordinary income (wages, dividends, etc.) per year with a capital loss. So, our hypothetical $5,000 loss would be divided into a $3,000 adjustment to income, and a $2,000 carry forward into the next year.
The next year, the $2,000 can be used to offset a capital gain, or ordinary income.
If you held investments in a non-qualified account (i.e. not an IRA or 401(k)), you probably had significant losses in 2007 and/or 2008. Those losses would have carried forward into 2009 and later, offsetting future capital gains.