Used both literally of the most highly personal feature of a human being (e.g. Matt. 26: 67) or metaphorically (e.g. Isa. 3: 15). It is used of Moses speaking personally to God (Exod. 33: 11), and in 2 Cor. 4: 6 Paul uses the face of Jesus, meaning the person and work of Jesus considered as a complete whole.
To speak of God hiding his face is a very common way of explaining misfortune in the OT.