Searching around yielded little to no results to answer your questions. However, after you provided the images of the posting, I was able to translate this imagethis image using Google's Image translator app on my phone. Although:
Although it's not perfect, every time it seemed to come to the conclusion that the bottom bullet basically says "No software on Side B, new software can be written."
Due to what little is available about this, I would believe that this game is only one sided-sided.
Side note: I got some interesting translations, like the red text in the above image saying "Fur Peeler" - I think the red text says "Family Computer Disk System" but the plastic on the game case blurs it somewhat in the image
Edit:
The eBay listing stated that it contains "Super Mario Bros 2 + Volley Ball", so this particular disk seems to have two sides, but for two different games.