Employment is fundamental to your identity, self worth, and personal well-being. From an individual as well as an organizational perspective, it's the biggest investment there is. You would not buy a house without legal advice – take the same approach to employment. Remember you have rights. Being informed is the best tool to ensure you understand your rights and they are being protected.
The letter of offer or employment contract must set out the purpose of a probationary period including how performance will be evaluated; what happens if the Employee is unsuccessful; and what will be paid on termination of employment?