。
She started her homework right away.
Literal
She [topic-は] right-away homework [object-を] started.
宿題 ('homework' — literally 'lodging task', from the idea of a task taken home with you) is one of the central nouns of Japanese school life, where homework often piles up significantly compared to many other countries. 始める ('to start / begin') is the transitive partner of 始まる ('to begin', intransitive). With を marking the object started, the pattern ~を始める covers everything from physical actions (work, projects) to abstract endeavors (study, plans).