I observe that the blades are slanted to an angle, but if it produce a lower pressure in one region, is it not possible that the wind from both side will go in?
Take a ceiling fan. If the blades were not slanted, as the instantaneous momentum of the rotation will be in the plane of the blades, only the thin sides would move air, very inefficiently.
Slanting the blades pushes air in a perpendicular direction to the plane of rotation , the air filling up the vacuum behind comes in the same direction as the one pushed, so an overall draft is established. The direction of the wind depends on the direction of the slant with respect to the direction of rotation.
A a draft is built up , directed where change of air is needed.