。
She screamed in pain.
Literal
She [topic-は] painful [and so-くて] scream [object-を] raised.
痛くて uses the て-form of the i-adjective 痛い ('painful') to express cause: 'because it was painful.' 悲鳴を上げる ('to raise a scream') is the standard expression for screaming — 悲鳴 ('scream,' literally 'sad cry') combined with 上げる ('to raise'). The causal て-form of adjectives is a productive pattern: 嬉しくて泣いた ('cried from happiness'), 怖くて逃げた ('ran from fear').