Unrealized losses mean simply that, losses not yet realized. Imagine you bought $10,000 of Dogelonmarsfart Inu token, expecting it to go to the moon. It pumps 2x and your coins are now worth $20,000, you now have $10,000 in unrealized gains. Then the Bogdanoffs make the call and Dogelonmarsfart Inu dumps so hard your investment is now only worth 1/100th of the initial principal, or $100. Because you're a ride or die diamond hands ape to the end, you still don't sell, you now have $9,900 in unrealized losses.