。
She's the teacher's favorite.
Literal
She [topic-は] teacher [possessive-の] favorite is.
贔屓 (ひいき) means 'favoritism' or 'patronage,' and ご贔屓 adds the honorific prefix ご. The kanji 贔屓 are notoriously difficult — among the most complex characters in common use — and the word is frequently written in hiragana as ひいき instead. Being 先生のご贔屓 (the teacher's favorite) can carry both positive and negative nuances depending on context.