A probation period is an initial phase of employment during which either the employer or the employee can end the contract with shorter notice, used to confirm the role is a good fit. In the UAE it cannot exceed six months.
Probation lets both sides assess the match before fully committing. During it, notice requirements are shorter than for confirmed employees, and there are specific rules in UAE law about notice and moving to another employer.
Good practice is to run a proper probation review before the period ends — confirming, extending (within the legal limit) or ending employment deliberately, rather than letting the date pass by default.