This is what I am most concerned about. However, UBC is likely to know more than you might expect about how grade scales typically work in your country.
This leads to the obvious question: Do you know how strong your grades are compared to other students in your high school? For example, do you know whether you are in the top 10% of students in your high school?
Also, why UBC? While it is a very good university, there are other very good universities in Canada also. For example, the University of Victoria and Simon Fraser University are also very good. There are many other very good universities in Canada. Somewhere like Ryerson in Toronto is likely to be easier to get accepted to compared to UBC.
Also, what is your budget? Full scholarships are rare in Canada.
Your internship at Citibank is likely to be helpful. It is hard to predict how much impact this will have on your acceptance, but it sounds like a good thing to do that should help you in several ways.