It means you're getting your money in good but are having bad luck if the AI EV line is above your earnings line. Kind of like Sklansky bucks. Good way to measure your decision making, and add confidence.
That line can be misleading. For example, if you go all in holding AA vs someone holding KK and win, your results will be above your EV line. That is because even with AA vs KK, your EV is not 100% of the pot since sometimes you will lose to KK.
So basically, what I'm saying (and what has been explained way better than I just did in a few older threads) is that you should not pay too much attention to this line.