。
She is a qualified nurse.
Literal
She [topic-は] nurse [possessive-の] qualification [object-を] holds.
看護婦 is the older, gendered word for 'nurse' (婦 = woman) — replaced in formal usage by the gender-neutral 看護師 in 2002, when Japan's healthcare law was rewritten to remove gendered occupational terms. You'll still encounter 看護婦 in older writing, dialogue, and casual speech, but on hospital documents and signage it's now uniformly 看護師. The phrase 資格を持っている ('hold a qualification') is the standard way to say someone is professionally licensed — the verb 持つ ('hold') ranges from physical to abstract possession. Worth noting that 看護師 covers both male and female nurses; 看護士 (with 士 'practitioner') was briefly used for men before the unified 師 form won out.