That's not a terribly bad or involved repair as repairs go, but it will take a bit of work. It's definitely gone completely through the outer layer of fiberglass. depending on how long it's been like that, it's allowed moisture to get into the foam core, which will hasten delamination/soft spot formation. The sooner you seal it back up, the better. It's something that it'd be prudent to get repaired right away, but, it's not something that will break the boat if you don't fix it first.
The fix is pretty simple. You've gotta sand through the gel coat, then the outer layer of fiberglass, until all of the exposed glass is semi-translucent (just sanding off the gel coat you'll see white, fractured fibers. This is damaged fiberglass, and needs to be sanded out for a proper repair). I'd stop sanding just before reaching the foam core. The damage for something like that goes deeper and spreads out further than it looks. I'd bet it's a ~4" diameter area that needs repair. Once it's fully sanded out/opened up, you'll cut a few pieces of fiberglass cloth and/or mat to build the area back. Then you'll need to mix polyester resin & catalyst, "wet out" the pieces of fiberglass, apply them to the repair area and cover the repair. Once it hardens completely, sand it down a bit, mix some gel coat and apply it over the repair. Then sand it flush with the original hull. It'll take probably 8 hours total, spread out over 2-3 days (cure times).
https://www.youtube.com/watch?v=i9hfpOCnzEshttps://www.youtube.com/watch?v=gGr-OsU ... ion_604527https://www.youtube.com/watch?v=0-kVRKhyb3ghttps://www.youtube.com/watch?v=5MWN7kbzutMThese videos provide a VERY thorough explanation of the why's and how's to fiberglass & gel coat repairs. It really is simple once you have all the material, it just takes time.
Just do yourself a favor and try pressing down all along the length of the deck and even on the sides, especially if you find any bulges or bubbles. Don't be afraid to put some weight into it! The boat can take it! If you hear a crunch at any point, or it feels soft/spongy/springy, you've found a soft spot. Anything else can be repaired (soft spots too, if they're not very large), but the hulls are the most irreplaceable part of the boat. Take a look at the bottoms for wear, check along the lip of the hulls for cracks/separation, check inside for standing water. Just about anything can be fixed on these boats, including most of what I've listed off here. It just depends on how much time, money & effort you're willing to put into it. If it needs a lot of work or has very large soft spots, you might be better off looking for another boat.
If you get to looking it over and have any more questions, feel free to ask!