。
She looked at her figure in the mirror.
Literal
She [topic-は] mirror [with/by means of-で] own figure [object-を] looked-at.
Note the で here marks the mirror as the means/instrument — 'looking by means of the mirror' — rather than its location. This usage emphasizes the mirror as a tool of viewing rather than a place. 自分の姿 ('one's own figure/appearance') is the standard phrase for 'one's image/look' in a reflection or photograph context. 姿 is broader than English 'figure' — it covers shape, form, posture, and overall appearance.