铁板一块

Traditional (Taiwan): 鐵板一塊

tiěbǎnyīkuài ㄊㄧㄝˇ ㄅㄢˇ ㄧ ㄎㄨㄞˋ

    • solid unit that cannot be broken up
    • firmly united or impenetrable bloc

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
a single slab of iron
Meaning
A solid unit that cannot be broken up, usually a group that is firmly united. It can be approving or can describe a bloc that is impossible to penetrate.

Sources