2P rules wrote:
The map’s terrain and other key features are
identified in the map’s terrain key. The primary in-hex
terrain types are clear, broken, woods, forest and city.
Road, town and Westwall are terrain features that can
appear in the terrain types. The primary hexside terrain
feature is river.
FWIW I understand it to mean each hex has (exactly) one of the 5 terrain types (clear, broken, woods, forest and city) (and that whatever is graphically the most dominant/prevalent in a hex determines which of the 5 it is), and that hexes possibly also have road, town and westwall as additional features on top of their (single) primary terrain type.
(But I agree it's not clearly spelled out.)