、。
Before going on stage, she rehearsed her lines once.
Literal
She [topic-は] stage [onto-に] go-out before, one-time own [genitive-の] lines [object-を] re-recited.
~前に ('before') attaches to a verb in plain non-past form regardless of when the action actually happens — 食べる前に ('before eating'), even if the eating already occurred. Tense in the matrix verb (here 復唱した, past) sets the actual time. ステージに出る ('go on stage') uses に as the destination of motion. せりふ (台詞 / 科白, often written in hiragana) is the standard word for actor's lines or scripted dialogue. 復唱 ('recitation, reading aloud') is a Sino-Japanese compound built from 復 ('again') + 唱 ('chant, recite').