。
She looked out the window.
Literal
She [topic-は] window [from-から] outside [object-を] looked.
窓から (with から marking the location through which one looks) is the standard construction for looking out a window. 外を見る ('look at the outside') treats 外 ('outside') as the direct object of 見る. The combination 窓から外を見る ('look at the outside through/from the window') is the full standard phrasing.