Getting weird spots  

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This looks like a combination of three minor problems: 

Your first layer calibration is suspect and there seem to be dirt and fingerprints on your print-bed.

Clean the sheet with dishwashing detergent (Dawn/Fairy) and plenty of HOT water, rinse well and dry with a fresh paper towel. Handle by the edges only.

At the end of your first layer calibration you are aiming to print a single layer *sheet*.  It should be possible to peel it off in one and fold it without the threads seperating. If it breaks into lines it is too high, not squished enough. If it is a single sheet but with wavy lines or drag marks on it you are too low.

For most people it pays to use 7x7 mesh bed levelling.

Many beginners have problems with the built-in first layer calibration routine. There are alternatives, see this page by a regular poster here: http://projects.ttlexceeded.com/3dprinting_mk3_live_z_calibration.html

and look at this thread: https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

Also look up threads here about drying filament, I am less cerain about this but I also suspect your filament may have absorbed moisture from the atmosphere.

Cheerio,

Adjust your Live Z down

Your first layer is to high. make sure your sheet is clean, as Diem mentioned.

Good Luck

Swiss_Cheese

RE: Getting weird spots

Jon, I can atest to the cleaning of the sheet making a huge difference.  I am new to printing too but a few people on this site really helped me out.  At one point I was able to print the frog that comes with the printer at -1.100 and thought I was good, but I was still too high.  I could not print a benchy at that level and ended up with a decent benchy at -1.207.  My point is that you could need to make a big adjustment but just keep messing with it and you will get it.

RE: Getting weird spots

Thank you for all of this! I made some adjustments and cleaned the sheet with detergent. Is this better than using IPA alcohol? 

@hogan89

Thank you for all of this! I made some adjustments and cleaned the sheet with detergent. Is this better than using IPA alcohol? 

Yes in fact it is, however IPA is OK in between prints. just wash the sheet every 4 or 5 prints if printing in the same area repeatedly. or after printing on the entire sheet several times, this helps to remove oils from your finger tips and spots that IPA just doesn't seem to get rid of.

I actually tend to clean my sheet with 100C+ water, from an instant hot water spout that I have at my sink, and don't even find the need for detergent. i rinse and dry with a clean paper towel.

Regards

Swiss_Cheese