A Statement of Purpose (or an SOP), is written to an admission panel of a university and constitutes details about your career path, interests, professional contributions, goals, and your end goal behind pursuing the particular program. This is the most integral part of your application and determines whether you are accepted into your institution of choice.
In short, a well-written SOP for Canada shows your overall personality to college. This is your chance to explain to the committee your purpose and why they should choose you over other applicants. A well-written SOP also mirrors how well you can set your thoughts with your writing skills.