。
She's in her prime as a woman right now.
Literal
She [topic-は] now woman-prime is.
女盛り literally compounds 'woman' + 'peak,' an old-school way to describe a woman in the most vital and flourishing years of her adult life — typically late twenties through forties, depending on who's speaking. Parallel to 男盛り for men, and to broader 盛り compounds: 食べ盛り ('peak eating years' for growing kids), 働き盛り ('peak working years'). Modern speakers may find the term faintly dated, but it remains in literary and journalistic use, often nostalgic. The bare だ keeps things plain and assertive — a fitting register for a slightly old-fashioned phrase.