LMO stands for Labour Market Opinion. If an employer wants to hire a foreigner, he needs to apply for an LMO to Service Canada. He might have to show that he advertised the job already and that he could not find anybody and he needs to show that he is offering market wage. If Service Canada approves it (positive LMO) they give the employer a document. The employer gives the document to the worker and the worker applies for a work permit.