mask, face, features, surface
面 centers on the front-facing aspect of something: the face itself, a mask that covers it, the surface of an object, or the visible features that define its appearance.
interesting; fascinating; intriguing; enthralling
face
face; mug
face
screen (of a TV, computer, etc.)
trouble; bother
serious; earnest; sober; grave
scene; setting; place (where something happens); scenario; case
good-looking guy; handsome man; hunk; Adonis; cool guy
surface; face
direction; district; area
interview (e.g. for a job)
front; frontage; facade; main
mask
whole surface; entire
area (measurement); square measure; size (of land); floor space
side; flank; profile; sidelight; lateral
bothersome; tiresome; bother to do
ground; earth's surface
face (of person)
confrontation
while; although; though; but
front part; frontage; facade
meeting face-to-face; seeing in person
面 is a pictograph of a face, with the outer box representing the outline and the inner strokes suggesting the eyes and nose. The modern form retains this stylized face shape.
The outer box is the outline of a face, and the inner strokes are the eyes and nose. Together, 面 is a face or mask, and by extension any surface or set of features.
For メン, imagine a man putting on a mask: man -> メン, and the mask covers his face.