。
She quoted from a Keats poem.
Literal
She [topic-は] Keats [of-の] poem [object-を] quoted.
John Keats (キーツ, 1795–1821) was one of the leading English Romantic poets — alongside Shelley and Byron — known for sensuous, lyrical odes like 'Ode to a Nightingale' and 'To Autumn,' written in a brief, fever-bright career cut short by tuberculosis. He's well-represented in Japanese English-literature curricula, often introduced via translation alongside Wordsworth and Shelley. 引用する ('quote, cite') is the standard verb for citing language from a source. Foreign personal names are written in katakana with original-language romanization rules transliterated phonetically: Keats → キーツ.