？
Have you decided where you'll study abroad yet?
Literal
Study-abroad destination [topic-は] already decided?
遊学 (ゆうがく) is a somewhat old-fashioned or literary term for studying away from home — broader than 留学, which specifically means studying abroad. 先 ('destination') is attached directly. もう決めた？ is the casual past-tense question ('already decided?'). Particle omission (no を after 先) is natural in casual speech.