お面 is read as おめん (omen) and means mask.
おめん
omen
げめん
outer surface
つら
cheek meat
みなも
water's surface
おも
face
ばめん
state of the market
ひょうめん
appearances
いちめん
(on) the other hand
しょうめん
front
ほうめん
direction
がめん
screen (of a TV, computer, etc.)
はんめん
half the face
そくめん
aspect