By selecting 'Private,' the owner has no rights to reproduce or use the work commercially. By selecting 'Limited Reproduction Rights,' the artist grants the owner full commercial rights for the work to be used or recreated in commerce, but does not give away the creator's license.
That is what NFTShowroom says about the rights you as an minter can chose when minting.
I am also a bit lost on all of that, and also not really in the business so didn't really got deep into it.
Edit:
Just seen that you commented on it in the next comment.
I don't quite understand why they would come up with such confusing definitions. In the "real" world of copyrights, I post a lot of my stuff as CC, but with the restriction of "Attribution-Non-Commercial-No Derivatives": https://creativecommons.org/licenses/by-nc-nd/2.0/
So why they tried to re-invent the wheel is beyond me, since all these different licenses are already part of the legal framework of Copyright and Creative Commons.
More about Copyright on my Visionary Art website.