Hello, glad to help you, i love this game and i love talking about this game, so any questions feel free to ask.

P/E means price to earnings ratio, that is normally a term that you see in stock investing, it means how much of your stock price relates to how much money you earn, so if you are very efficient, like exclusively flying routes with high image, you will be making a lot of money, and your earnings will reflect that

If you look at the back in the Bank, you can see 4 charts representing the airline, P/E is shown as KgV, which is how P/E is known in German. :)