It's generally okay for international students to apply for undergraduate programs in Canada, even if their high school education was in a different field. Admissions decisions typically depend on the university's requirements and the applicant's overall qualifications. While studying real estate after a business-focused high school might not be a direct continuation, it's not an automatic reason for visa refusal. Visa officials consider various factors, including your genuine intent to study and your financial ability. Be sure to provide a well-reasoned explanation in your application to address any potential concerns.