班主任都是容嬷嬷转世
[bān zhŭ rèn dōu shì róng mā mā zhuăn shì]
Here, class advisors (usually strict educators overseeing students in school dormitories) are being compared to 'Lady Rong,' an authoritative figure well-known from a Chinese drama, indicating how these adults can seem extremely strict or unfriendly, even oppressive, like reincarnated versions of Lady Rong.