I can advise the Deputy that in order to work and reside in Ireland a non-EEA National, unless they are exempted, must hold a valid Employment Permit and an appropriate immigration permission. The Department of Enterprise, Trade and Employment (DETE) administers the Employment Permits system.
Any non-EEA national that is unsure as to whether they require an Employment Permit should contact DETE. Full details can be found at the link below: dbei.gov.ie/en/What-We-Do/Workplace-and-Skills/Employment-Permits/
If the non-EEA national is unsure as to whether they require a visa/preclearance to enter Ireland they can check their nationality on the list at the following link:
www.irishimmigration.ie/wp-content/uploads/2021/07/Immigration-Service-Delivery-Visa-and-Non-Visa-Required-Countries.pdf