Meaning
An open hand raised and waving, usually shown with a few motion lines. It says hello or goodbye, and can also be a friendly way to get someone’s attention.
It is a natural opener for a first message or a quick check-in: “Hi Ms. Lan 👋 just following up on yesterday’s order.” It works as a friendly sign-off too. After an argument, though, a lone wave can sound like a curt “bye,” and some people use it to wave someone off sarcastically, so add words when the mood is tense.