Prefinished means it has already been coated and sealed with translucent film which serves as its protection from daily wear. What finishings can do is shield your hardwood floor from spills and scratches, and make it easier for you to wipe or mop clean.
If you're thinking of installing hardwood flooring yourself, you can enjoy the greatest ease and convenience with prefinished planks. With prefinished hardwood floors, the task of nailing the flooring to your subfloor ends after the drilling is done.
If you purchased pure hardwood oak or maple (or whatever is available), you will have to apply finishings, sand it down and put on wax and polishers after. The amount of time to perform the task of installing a hardwood floor is halved if prefinished wood is used.
Prefinished floors also have a better finish than most independently finished floors. Because the application is uniform and the volumes of coating controlled and predetermined, you are sure that every prefinished hardwood floor plank is of the best quality. Normally, prefinished floors are thrice sanded and coated with aluminum oxide finish eight times. They are also likely to have been tested for various normal wear situations and made more resilient.
Prefinished flooring is a little more expensive than pure hardwood planks. However, when you do the math on everything that has to be done to make the basic form shine to your liking, you'll actually eventually spend a lot more with the latter, not to mention the heavy labor that you need to put into it.
Sure, you can argue that you can always hire professionals to do the job for you, but if cost is an issue, then you'll be thanking the high heavens that somebody had enough foresight to come up with prefinished hardwood flooring. Be a wise and practical consumer. Sanding and finishing entire floorings is a thing of the past. Now that prefinished floors are available, you should spare yourself from the hassle.
