。
She was raised by her grandmother.
Literal
She [topic-は] grandmother [by-に] was-raised.
育てる (そだてる) means 'to raise' or 'to bring up,' and the passive 育てられた puts the focus on the person being raised. The に marks the agent — the person who did the raising. This is a standard direct passive construction, parallel to English 'was raised by.'