。
She was late to school.
Literal
She [topic-は] school [target-に] arrived-late.
遅刻する ('to be late, arrive late') is the formal verb for tardiness — 遅 ('late') + 刻 ('time, hour'), literally 'late-time-ing.' It specifically refers to being late for a scheduled commitment (school, work, an appointment), distinct from plain 遅れる ('to be delayed, lag behind') which is broader. に marks the place or event one was late *to*. 遅刻 carries social weight in Japan, where punctuality is a heavily enforced norm — being late to school could trigger anything from a sharp word to a written report depending on the school's culture, and 遅刻が多い ('frequent tardiness') goes on academic and employment records.