Most foreign nationals need a work permit to work in Canada.
There are 2 types of work permits.

Employer-specific work permit
An employer-specific work permit lets you work in Canada according to the conditions on your work permit, such as:
The employer who wants to hire you must complete certain steps and give you either a copy of a Labour Market Impact Assessment or an offer of employment number to include in your application.

Open work permit
An open work permit lets you work for any employer in Canada.
You can only get an open work permit in specific situations.
You may be eligible for an open work permit if you:

• are an international student who graduated from a designated learning institution and are eligible for the Post-Graduation Work Permit Program
• are a student who’s no longer able to meet the costs of your studies (destitute student)
• applied for permanent residence in Canada
• are a dependent family member of someone who applied for permanent residence
• are the spouse or common-law partner of a skilled worker or international student
• are the spouse or common-law partner of an applicant of the Atlantic Immigration Pilot Program
• are a refugee, refugee claimant, protected person or their family member
• are under an unenforceable removal order
• are a temporary resident permit holder
• are a young worker participating in special programs