Meaning
The letters OK on a square button. It means okay: agreed, fine, approved or understood.
It is one of the quickest replies in any chat, whether you are confirming a time, accepting a task or ending a discussion politely: โ7 pm at the cinema? ๐โ Some find a bare ๐ a little cold, so adding ๐ or ๐ softens it. Its opposite is ๐.