My new job has a "90-day trial period". What does that mean?

Any employer can now include a trial period of up to 90 days for a new employee who has not worked for them before. It is only valid if it is written into your employment agreement and you signed the agreement before your first day of work; you must also be given a fair chance to get independent advice on it. During a valid trial the employer can end your employment without you being able to bring a personal grievance for unjustified dismissal. Everything else still applies: you get the minimum wage, holidays, sick leave, and full protection against discrimination, harassment and unpaid wages. Source: Employment New Zealand — https://www.employment.govt.nz/news-and-updates/90-day-trial-periods-extended-to-include-all-employers