I have been a nurse for over 12 years, and I think that the test you are referring to is a general ed-type test. Almost like a milder form of the ACT/SAT. Of course, I might be wrong on that.
Basically, if you are not that far from just being out of school in general, you should be fine with a good night's sleep. Otherwise, if it's been a while, I would brush up on your math, since that really is a big issue with medication errors in calculations.
I think that this test just might be to see if you have the general basics that will be applied later in your nursing program. I doubt that they will ask any medical questions unless I am WAY off on my idea of what this test is.
Good luck and let us know how you do.