If you are from a country that is not in the European Economic Area (the EU, plus Norway, Iceland and Lichtenstein), the UK or Switzerland, you need permission to work in Ireland. In most cases, this means you have to apply for an employment permit.
The General Employment Permit allows you to work in occupations where there is a labour shortage in Ireland. You can get the permit to work in any job that is not on the Ineligible List of Occupations for Employment Permits, and subject to the other qualifying criteria.