Resolved questions
这句话的意思是什么?

If you know English, it means: Hello, people who are (or live) upstairs.
If someone said this to me, maybe he/she live/at downstairs
.

มารยาท

Upstairs hello intention refers to live in their own home upstairs household greetings, but now many said for BBS on within a user's greetings

as a matter of fact, it always appears in the words as a beginning for replies.
for example:
someone posted " It's so difficult to learn Chinese."
someone replied "I'm chinese, so I don't think so"
you made a reply " 楼上你好（hello, man above), you're chinese, so ,can you tell me how to learn chinese in a simple and systematic way".