Meaning
The word COOL in capital letters on a square button. It means cool in the everyday sense: nice, stylish, impressive or simply fine.
It is a compact way to approve something, from a new haircut to a change of plans: “Meeting moved to 3? 🆒 works for me” Some use it with a wink for things that are literally chilly, like air-con or iced drinks. Pair it with 😎 for extra attitude.