The default setting is Left to right. This means that the wind direction reference is the boat course as if you were sailing from left to right side of your screen. So in the planner diagram it is the “relative true wind” you observe on the boat. (Note it is not the relative wind resulting from the true wind and the boat speed).
As @Ondřej-Šutera said, click More option and choose North up to show a more conventional direction of the wind
However Left to right is an alternative to North up because it shows when your route is heading into the wind or is too close to the wind direction. It shows the angle of the true wind to the boat.