Will I see parabolas on the GRE?

In all honesty, it is fairly unlikely that you will see a parabola problem on the GRE. It is an uncommon topic that only comes up if you are in the top scoring cohort, and even then it isn't a guarantee.

Despite that, you should do at least do a basic review of the concepts related to parabolas. I think you'll find this article helpful for tackling the basics of parabolas!