。
She has been sickly since birth.
Literal
She [topic-は] born time [since-から] sickly was.
生まれた時から means 'since the time she was born' — a relative clause (生まれた) modifying 時 (time), plus から (since). 病弱 (びょうじゃく) means 'sickly' or 'of poor health' — 病 (illness) + 弱 (weak). The past tense だった frames this as a lifelong state observed looking back.