I think it looks like;
Kids who know their teacher cares about them
Kids who know what is expected of them
Well organised routines and procedures
Consistent, logical consequences
A calm teacher
It definitely doesn't look like perfection though

Kids make mistakes, chaos happens, learning is often noisy and sometimes quite messy.
Kids will behave badly at times- good classroom management does not mean zero bad behaviour, it just means that bad behaviour is responded to appropriately when it happens.