。
She was raised by her grandma.
Literal
She [topic-は] her [genitive-の] grandma [agent-に] was-raised.
おばあさん is the warm, colloquial word for grandmother — the kind you'd actually call her or use in casual conversation. The formal/written counterpart 祖母 (そぼ) is used when referring to one's own grandmother to outsiders or in writing. The construction is a direct passive: 育てられた (passive past of 育てる, 'raise') + agent に on the grandmother. The doubled 彼女 reads as stilted — a native would simply say 彼女はおばあさんに育てられた, dropping the second 彼女 once she's the topic.