The zero tolerance in the workplace means that if you violate a rule in the workplace or do anyone harm in the workplace or harass someone on the workplace then you could be fired as a result without any other warning.
The zero tolerance policy in a workplace is a way to eliminate undesirable behavior among employees and provide an automatic punishment for the employee violating company rules.
The zero tolerance policy can also mean customers are told right away to leave the premises if they violate any rules of the workplace and could even have the police called on them.
Such as for violence, verbal abuse or other harm, threats etc then you can be banned from the premises.
If you do not leave then the workplace could call the police to have you removed.