Probationary period
Explanation:
A probation is a period to see if a new hire (or new promoted worker) is suitable for their job or not. The person also can see if they like the new career or not. Depending on the company, the probation normally takes between 3 and 6 months.
The probationary period of the worker may be increased under some conditions. Extensions may be caused by a shift of duty or oversight leave took during the probationary period, etc.
Employment at will implies that an individual can be remitted without notice for any cause, unless the reason has been unlawful. Probationary periods for workers may be disadvantageous.