。
She was blessed from birth with a sound mind and body.
Literal
She [topic-は] innately healthy spirit [and-と] body [with-に] was-blessed.
健全な精神と肉体 means 'a sound/healthy mind and body' — 健全 (けんぜん) means 'healthy/sound,' 精神 (せいしん) means 'spirit/mind,' 肉体 (にくたい) means 'physical body.' The phrase echoes the Latin ideal of 'mens sana in corpore sano.' ~に恵まれていた puts this in the past progressive, suggesting an observed state at some past point.