。
My room gets the afternoon sun right in the face.
Literal
I [of-の] room [topic-は] west-sun [object-を] head-on receives.
西日 literally 'west sun' = the afternoon/evening sun from the west. Rooms with a western exposure get hot and bright in the afternoon — a common complaint. まともに ('directly, head-on, full-on') intensifies 受ける ('to receive'). A very Japanese way to describe a room's solar exposure — the room is the grammatical topic, and the sun is its object.