What does must serve grievance notice on the employer mean?
It says this is one of the requirements to satisfy in order for there to be an action for unfair dismissal, i.e the employee takes the employer to court for unfair dismissal.
It means that the dismissed employee must tell the employer that the employee feels that their dismissal is unfair and that they are considering taking further action to persuade a Court or a tribunal that, in fact, that dismissal IS unfair