Term 3 means that the course is taken over the full year (both semesters). It would have a course code that ends in 6, i.e. French 1A06. Math 1LS3 is offered both semesters, so if you took it 2nd semester you would have 5 courses each semester.
As for electives, they don't necessarily have to be science electives. You do need 6 units (2 courses) in Science (Chem, Bio, Enviro Sci, Psych), but you can take those in any of your 4 years. You have the math requirement covered by taking Math 1LS3, and then eventually you'll have to take either Stats 2B03 or Kin 3C03 (most likely in 3rd year).
Hope this helps, and if you have any more questions let me know.