。
She screamed at the top of her lungs.
Literal
She [topic-は] voice [object-を] limit [to-に] screamed.
声を限りに叫ぶ means 'to scream at the limit of one's voice' — at maximum volume, holding nothing back. 限り (かぎり) means 'limit' or 'extent,' and 声を限りに is a set phrase for giving everything vocally. 叫ぶ (さけぶ) means 'to shout' or 'to scream.' The expression is dramatic and literary.