What does this report code mean and what do I do?

Yes, the report code shown in that spot will change as it indicates what state the game is currently in. You can disregard all of them unless you are actively having an issue with the game.

I got this error code now

So it can be used for problems other than terminal errors that don't normally generate a pop-up style error code.

uhh ok... but why does it show?

rr07y53x3ljb​  The report code is there in case you need to report an issue. If you are not currently experiencing an issue you can ignore it.