MBG_orientation for flow direction

I’m having a hard time figuring out the MBG orientation and how to represent it in a accurate way. My work consists in mapping boulder deposits (shapefiles) and with the MBG convex hull to assign them a direction. However I don’t understand how to interpret the data on the MBG_Orientation column? I’ve understood it’s on 180 degrees only but which direction means which number (north, south, east & west- wise)? For example most of them are around 80 & 90 degrees which I would assume is a eastern direction but I’m not sure and would like to understand how it works.

Also, I would like to use the rotation symbology so as to show direction with arrows…and this gets event more complicated for me, if you could help!