On a map or graph, east would be a vector pointed to the right. 50 degrees "north of east" would be a vector that points 50 degrees counter-clockwise from the right. This is the convention used for polar coordinates, 0 degrees pointing to the right, along the "X" axis, and positive angles associated with counter clockwise angles. East is 0, north is 90, west is 180, south is 270.
Navigation uses a different convention. 0 degrees means to the north ("Y" axis), and positive angles are associated with clockwise angles. North is 0, east is 90, south is 180, west is 270 (degrees). Airport runways are normally named after the direction divided by 10. An east / west runway would be called runway 90 if approached from the west heading east, and runway 27 if approached from the east headed west.