Meaning
The letters UP with an exclamation mark on a square button. It means up, rising or levelled up, with a bit of extra energy.
Gamers use it for levelling up, and people celebrate promotions or personal progress with it: “Passed the driving test, life 🆙” In buy-and-sell groups, commenting “up” under a post is a common way to bump it back to the top, and 🆙 does the same job.