I understand what 눈치 means, but don't know how I would describe it to someone who does not know what this is.
The best way I would describe it to someone would be
to have an awareness of your surroundings and others
Someone that doesn't have it could be considered to be clueless, doesn't pick up on social cues, and overall unaware of gauging the atmosphere and adjusting to it.
Would this be a decent explanation of this term?