Hi Destiny,
The ghost touch phenomenon occurs when the signal lines between the motherboard and the screen's digitizer are damaged and start allowing electrical noise on the lines. That noise gets picked up by the phone and interpreted as screen touches, causing the problem you're seeing.
Unfortunately, that sort of damage isn't repairable; the only solution is to replace the digitizer. There's one small catch to that, though; the digitizer is bonded to the OLED display and can't be replaced separately, so you ultimately have to replace the entire screen to recover from the problem.
The good news here is that iFixit has you covered! They have a guide giving you step by step directions on how to replace the screen, and if you want to support their repair efforts, you can even buy the screen right here on this site.
[guide|133913|Samsung Galaxy S20 Plus Screen Replacement - iFixit Repair Guide]
If you're new to phone repair, I'd suggest splurging the extra $7 to get the Fix Kit version that has the screen plus all the tools and adhesives needed to do the job right.
[product|IF437-001-2|Samsung Galaxy S20+ Screen]
If you have the need to be cost conscious (the Samsung screens do tend to be a bit on the more expensive side), you can almost certainly find less expensive options on sites like Amazon, eBay and AliExpress, among others.
Good luck and let us know how it goes! We're always here if you have questions or need advice.