They might be talking about a specific trade? This needs more specifics before a specific answer can satisfy you OP. And besides, even with profit, you can still have losses in your history. Some traders tally each trade loss and profit, table them out, and based on the expected profit margin that they set up beforehand, they'd be able to calculate whether the trade they did for that specific time frame (most probably by month) is in profit or loss.

There's also the idea of transfer fees and probably some other misc fees they handle. Probably not that big for the most part but still part of the "loss" area.