少不更事

shàobùgēngshì
(idiom) young and inexperienced; wet behind the ears

CEDICT

young and inexperienced in life; wet behind the ears

Wiktionary

年轻而没有经验，阅历浅薄

維基詞典

Entry Composition

1 少 shào young
2 不 bù
  1. no; not so
  2. (bound form) not; un-
3 更事 gēngshì
  1. (literary) common occurrence, routine
  2. (literary) to experience
  3. (literary) to recur; to happen again
  4. common occurrence, routine
  5. to experience
  6. to recur; to happen again