。
She's already finished her work.
Literal
[topic-は] already work [object-を] finished.
もう ('already') paired with the polite past 終えました simply states that the action is complete, ahead of expectation. 終える is the transitive 'to finish [something]' — its intransitive twin 終わる describes the work coming to an end on its own. Note that the same もう attached to a question (もう仕事を終えましたか?) translates as 'yet' rather than 'already': English shifts the word, but Japanese keeps もう and lets the speech-act direction (statement vs. question) flip the polarity for the listener.