。
She's living abroad.
Literal
She [topic-は] overseas-life [object-を] is-doing.
海外生活をする is a tidy noun-plus-する construction: 海外生活 ('overseas life') + をする ('do, lead') yields 'lead an overseas life / live abroad.' Japanese builds many lifestyle expressions this way — 一人暮らしをする ('live alone'), 学生生活を送る ('lead a student life') — so getting comfortable with this template pays off. The ~ている marks an ongoing state: she's currently in the middle of that overseas life, not just visited briefly.