。
She married a banker.
Literal
She [topic-は] bank-employee [with-と] married.
結婚する takes its partner with と, which marks the co-participant in a reciprocal action. と is the standard particle for partners in joint actions: 結婚する, 話す, 戦う ('fight'), 別れる ('break up') all take と. 銀行員 ('bank employee') is built compositionally: 銀行 ('bank') + 員 ('member, staff'). The suffix ~員 productively forms job titles for organizational members: 会社員 (company employee), 公務員 (civil servant), 駅員 (station staff).