。
She is an ardent supporter of women's rights.
Literal
She [topic-は] women [of-の] rights-protection [of-の] enthusiastic supporter is.
権利擁護 pairs 権利 (rights) with 擁護 (protection/advocacy) — a formal compound common in political and legal contexts. 熱心な (enthusiastic/ardent) is a na-adjective modifying 支持者 (supporter). The formal copula である at the end reinforces the written, declarative register. The double の chain (女性の権利擁護の支持者) is a typical feature of formal Japanese noun phrases, building specificity layer by layer.