They're QR codes. They have been a big thing in Japan for sharing web links in adverts and such. All you have to do is point your camera at a code and it loads the text or webpage. It's been a standard thing in all Japanese phones since about 2005 IIRC.
Meanwhile they exploded into popularity in America in around 2011, but naturally they can't be read by basic phones here, you have to buy a $300 "smart" phone and download a specific app for it and pay for a data plan.