A Paracorr is a coma corrector made by TeleVue to correct the coma that is a natural by-product of paraboloidal mirrors. Hence, "Para" "Corr".
What is coma?
It is a stretching out of star images along radial lines (from the center out). In the center, there is no stretching, but the farther from center you go, the more stretched the star images.
The stars at the edge begin to resemble comets. Comets is a word from coma in Latin, which means hair. The constellation Coma Berenices means Bernice's hair.
So coma is an aberration that is present in all newtonian images, but which grows worse quickly the shorter the f/ratio of the scope.
No one thinks they need a coma corrector at f/6. By f/5 it's a generous percentage. By f/4.5 at least 50% feel the need, and by f/4 nearly everyone uses a coma corrector.
Your scope is f/5, so it's nice, but not absolutely essential unless you want the star images at the edge of the field to be just as small and sharp as they are in the center. Most people don't expect that, but once you have some experience with a scope where the stars literally are tiny pinpoints from edge to edge in the field, it's kind of hard to go back to having stars in the outer parts of the field look a little flared.
As a matter of exaggeration, the stars in a fast scope look a little like the stars from the flight deck of the Millenium Falcon jumping to lightspeed (in Star Wars) without coma correction, and look like the same field before the jump to lightspeed with coma correction. Of course, it's not that bad, but you get the idea.
Here's a good article to read on the subject: