。
She said that her failure was because she got sick.
Literal
She [topic-は] failed [explanatory-の] [topic-は] got-sick [because-から] is [quotative-と] said.
A complex reported speech sentence. The quoted content: 失敗したのは病気したからだ = 'the reason I failed is because I got sick.' This uses the のは~からだ pattern (the reason X is because Y) — a cleft construction that highlights the cause. と言った frames the whole thing as her claim. The sentence implies she may be making excuses.