It’s hard to tell exactly off photos, but that looks like some heavy light bleed. If it is as bad as it looks in the photos I’d have it checked out at the nearest Apple store. But that’s just my opinion.
EDIT: I just realized that you said you dropped the laptop. If it has been dropped and you don’t have AppleCare +, be prepared for them to say that they will want to replace the monitor and that will cost a lot, $600+.
If you AppleCare + I think it’s a $200 deductible for accidental damage repairs, although someone can correct me if I’m wrong.