You need to take 24 units (8 courses) in order to be considered full time and also be assessed for Commerce II.
In this case, it says 3-12 electives (1-4 courses) are required from that list.
It's really your choice to select how many electives you want to take
But like I said... You'll only be able to proceed to Commerce II only IF you have finished 8 courses successfully in first year.
Think about it this way.
In this program, you need a total of 120 units to be finished.
If you plan to graduate within 4 years, you should complete 30 units each year.
Either way, you'll have to make up those units to graduate if you choose to for example, take only 3 units of those electives for first year.
Maybe this would help too:
http://www.degroote.mcmaster .ca/UG/business1.html