。
She bore the pain admirably.
Literal
She [topic-は] that pain [object-を] admirably endured.
立派に ('admirably, splendidly, with dignity') is the adverbial form of 立派, a na-adjective that praises someone's conduct as fitting or honorable. Pairing it with 耐える ('endure') casts the endurance as virtuous — not just stoicism, but a moral achievement. Note 痛みを耐える uses を rather than the more common 痛みに耐える: the を form treats the pain as a direct object that's been overcome, while the に form treats it as the source one withstands. Both are used; the を form is slightly more transitive in feel.