It means that they have burned through half of their available cash in 6 months.

It means that if you read Virgin's press release, they talk about a small "operational loss." Regrettably for Virgin, they carry a lot of debt. That debt costs money. Hence the comment.

If you want to see how an airline is really doing, you have to look at the net loss/profit, not the operational loss/profit. Virgin has a significant net loss for the quarter they just reported.

Go to the press release section of the Virgin website. It's right there.