看臉色

Simplified: 看脸色

kànliǎnsè ㄎㄢˋ ㄌㄧㄢˇ ㄙㄜˋ

    • to read someone's mood and act accordingly
    • to show someone how tough one is

Character by character

Saying俗语俗語

Idiom惯用语 · In everyday use

Literally
look at someone's face
Meaning
Either to read someone's mood in order to act accordingly, often meekly, or to show someone how tough you are. Context decides which.

Sources