。
She will make a good wife.
Literal
She [topic-は] good wife become [probably-でしょう].
~になるでしょう combines the change-of-state になる ('become') with the polite conjecture でしょう ('probably, I expect'). 奥さん (おくさん) is an honorific term for 'wife' used when speaking of someone else's wife or politely predicting someone's future role.