Labor Market Impact Assessment (LMIA) is a document that a Canadian employer may need to obtain before hiring a foreign worker. A positive LMIA indicates the need to hire a foreign worker to do the job in Canada. It also states that no Canadian worker is available to do so. A positive LMIA is sometimes called a confirmation letter. If the employer requires an LMIA, he or she must apply. Once the employer receives the LMIA, the worker can apply for a work permit.

To apply for a work permit, a worker must have these conditions:

A letter of offer of employment; contract; a copy of the LMIA and the LMIA number.

You can read more at https://www.canada.ca