Meaning
The kanji 満 on a square button, meaning full in Japanese. On signs it means no vacancy: the hotel, car park or restaurant is fully booked.
It is handy for sold-out events, packed schedules and full stomachs: “Tonight’s show 🈵, see you next week” People also use it to say they are completely stuffed after a big meal. Its opposite is 🈳, which means space is still available.