。
She's a programmer.
Literal
She [topic-は] programmer is.
である is the literary/written copula, stiffer than だ or です — at home in narration, biographical entries, factual descriptions. Saying 彼女はプログラマーだ would feel slightly more conversational. プログラマー is a straightforward English-origin loanword; the trailing ー captures the English /ə/ schwa of '-er.'