Work permit visa on the basis of LMIA are the employer sponsored visas. To employ a foreign worker, an employer in Canada needs to prove that they tried their best to employ a Canadian permanent resident or citizen but could not get the required skills and experience that match the requirements.
You can work for up to 2-3 years for a specific employer in Canada depending on the contract you are offered by the employer. As this is a sponsorship based work permit, you cannot change your employer being on this visa. If you do wish to change employer, you would need to re-apply for the work permit on the basis of the new job offer and LMIA from the new employer. Work permit holders of this type can take their dependents along with them.
To find out more and to see if you qualify for a work permit to Canada please fill out the assessment form on this page.