The dropped course shouldn't appear on your transcript if you drop it by Nov 12th. After that, there are academic penalties. No, it won't matter for a job.
However, how many credits is this course that you want to drop? Because if it's 3, then you'll be registered in only 17 credits this year (assuming the 20 units you mentioned was for the whole year), and you will no longer be considered a full time student (requires 18 units). This may affect your OSAP and any scholarships, if you have them.