You don’t require a work permit to engage in business activities connected to your job back home, such as meeting with clients or attending conferences. If you plan to work in secretarial, management, technical, or production roles or stay in Canada for more than 6 months, you must apply for a work permit.
If you are in Canada on a permit for visit and receive a job offer from a Canadian business, you must apply for a work permit before you start working. Since your application must be processed by the Canadian office in charge of your nation of residence or citizenship, you may be obliged to leave Canada while your application is being processed. However, you can stay in Canada till the validity of your permit for visit expires.