You are only allowed one label for messages under General Discussion, BUT you can put any label you want under Message Tags.
See my test post here (EDIT: or not.... the post was deleted with supreme alacrity by an eagle-eyed mod...LOL) . Instead, see this screenshot of a post:
I used three random tags, including "outages." Clicking on the individual tags would help readers find other messages with the same tag across the community.
For labels, click on "general discussion is not a support area." It will then appear under "labels"
For other labels, use the "message tags" window. Just type in the labels you want.