In a general sense, the term "lærling" refers to any apprentice. However, it is also an official title used by public officials in Norway. In such cases, the correct English term is "clerical apprentice".
There are multiple definitions - click on the translation that matches your context.
someone who works for an employer for a specific period of time to learn a particular skill or job
This box and the toolkit it contains belonged to an apprentice working for the de Havilland Aircraft Company.