Err don't know how to explain that better.
You = Student, yourself, Kylieeee
Can = are able to, allowed, permitted
Enrol = the act of registration
In Whatever You Want = a colloquial phrase describing a situation of freedom.
So at an institution of higher learning, say like Macquarie University, they offer these things called "degrees". I know, two syllables, I'll let you take a moment to take it all in.
So these degrees, they have these re-quire-ments..basically things which you need to have completed/satisfied to be offered this degree at graduation.
Now, Com-merce, you see, has a few things you can 'MA-JOR' (MAY-JER) in, and those MAY-JERS can be found here
Its a lot to take in isn't it? I'll let you take a break again, go make a sandwich or something.
...Alright back? Ok, now this next part is very difficult. It requires YOU, yes that's right YOU, to LOOK at that page, and figure out what stream of study you want to actually do, so that you can graduate. These 'streams' will each have certain subjects or U-NITS (YOU-KNITS) that you have to do in order to graduate. So, basically, if you want to graduate in Commerce you have to follow those subjects.
Now the thing is, you don't HAVE to graduate, you don't HAVE to follow the streams, but you won't graduate with a Commerce degree, no biggie right?