APS is the score that universities use to determine whether you qualify for a certain course. It is worked out using your matric results. 

Note: At the end of grade 11, you can use your results to see if you would qualify for a course you want to take in university with the marks you got in grade 11. This will help you know how hard you have to work to ensure that you qualify for what you want to pursue. 

Your marks are converted to the points as seen on the table below, these points are then added, and the total you get is your APS. Each university allocates a minimal APS required to qualify for each course. These points vary depending on which university you're applying to; for example, you might need a minimum of 32 APS to study "course X" at "university A" whereas you only need 20 APS to stud the same course at "university B". Always make sure to aim for the highest APS you can possibly get to open up your options when applying. 

Of note is that Life Orientation is not awarded any points in some universities whereas other universities include it when calculating the score (be sure to check which category the university you're applying to falls under).