The KPI indicates how you are pacing MTD vs Forecast, Budget, and LY.
The direction of the arrow shows the trend compared to last year: an arrow pointing upwards means that the KPI is better than last year and vice versa.
A green arrow with a plus sign means that the KPI is better than the target (e.g. forecast, budget or last year, depending on the choice of target).
A red arrow with a minus sign means that the KPI is worse than the target (e.g. forecast, budget or last year, depending on the choice of target).