It means Peace Officer Standards and Training, which is the definition of the skills, attributes and expertise police cadets should have acquired by the time they take a position with a police department.
It means Peace Officer Security and Testing; this is the nationwide test all prospective police officers must pass before they can begin to serve on any police force.
It means Police Official Services Time, which is a schedule of the number of years a police officer must serve before collecting full retirement benefits.
POST refers to the location where a police officer is permanently assigned.