。
She was standing at the front of the classroom.
Literal
She [topic-は] classroom [genitive-の] front [genitive-の] direction [at-に] was-standing.
前の方 ('the front side / the front area') uses 方 ('direction, side') as a soft area-indicator — slightly looser than 前 alone, which would be a more pinpoint location. The に marks the resting location, with the ongoing-state ~ていた expressing 'was (in the state of) standing.' This kind of layered spatial phrasing is common in Japanese: a noun's relative position (前 'front'), modified by 方 ('side/area') for vagueness, anchored by に for location.