Hanging plastic part on car front end

It's probably the plastic air dam. (Could also be a piece of the front bumper cover, or fan shroud). You'll have to crawl under the car to see just what it is, the air dam helps direct air under the car and maybe keeps some water splashing up under the hood, it can be removed with little effect to the car. The fasteners holding it in place can be tricky, they'll either be your typical bolts/screws, or they'll be plastic fasteners like blind rivets. You can find a plethora of auto body fasteners at most auto parts stores, Napa has a pretty extensive selection. If the plastic piece is damaged beyond repair you can find a replacement at a local salvage yard or 'pull a part'. This is actually a great DIY project as it's likely just cosmetic damage not affecting the cars mechanical systems. (PS: RIP little porcupine.)