UBC just calculates on five approved grade 12 courses, can I choose which ones?

I'm not sure if it varies depending on which faculty you apply to, but typically they'll ask you to enter marks for all eligible Grade 11 and Grade 12 you completed. They will take your English 12 mark and three of the highest besides English 12 (I think it's three other approved courses, not four). Their requirements vary in different faculties, so look at the guidelines specific to the program you are applying to.