Meaning
The letters NG on a square button, short for no good, an expression widely used in Japan for something unacceptable or a failed take. It means not OK, rejected or a mistake.
It is handy for vetoing ideas, rating bad results and, in film and video circles, for marking bloopers and failed takes: “Behind the scenes: all our 🆖 moments” It is the opposite of 🆗, though many readers outside Japan may not recognise it, so a word of explanation helps.