。
She decided to study abroad.
Literal
She [topic-は] study-abroad do thing [to-に] decided.
留学する事に決めた — ことにする/決める ('decide to do X') expresses a personal choice. 留学する (りゅうがくする, 'to study abroad') is a common suru-verb. 事 is こと written in kanji.
。
She decided to study abroad.