。
She's thirty-five and in the prime of her womanhood.
Literal
She [topic-は] thirty-five-years woman-prime is.
女盛り is a culturally rich and somewhat dated noun: 女 ('woman') + 盛り ('peak, height, prime') = 'a woman in the prime of her life,' typically referring to physical and feminine peak. The mirror-image 男盛り ('a man in his prime') exists too but is less frequent. The traditional age range for 女盛り varies by source — sometimes 25–35, sometimes broader — reflecting older Japanese views about feminine 'peaks.' Modern usage carries traces of those associations and is not always neutral; depending on speaker and context, it can read as appreciative, nostalgic, or slightly old-fashioned.