。
She's a wonderful wife.
Literal
She [topic-は] wonderful wife is.
妻 (つま) is the standard, neutral word for one's own wife — paralleling 夫 (おっと, husband). Other choices have different registers: 家内 (かない, 'inside the house', traditional but seen as patriarchal today), 嫁 (よめ, originally 'bride / daughter-in-law', informal), 奥さん (おくさん, 'lady of the house', polite but used about someone else's wife rather than one's own). The plain copula だ keeps the register casual. The compliment is a role-specific one — praise of her as a wife and partner, distinct from a general 'wonderful person' compliment.