In the comments on both the question and answer on this meta question, I was having a brief discussion with two users regarding the degree of friendliness and openness TSE shows to new users.
OP brought to my attention one of their questions which has been closed as unclear.
It's not obvious to me why someone found this unclear. I'm sure the close voters had their reasons, but I have voted to repoen. However, this post is not a campaign to get this question reopened. What I'm saying is: When we cast a vote to close as "unclear what you're asking" I think it's pretty much our duty to also drop a comment explaining why, and requesting clarification. Nobody seems to have done that here.
The meaning of "on-hold" (rather than "closed) is that OP is supposed to be able to improve the question and perhaps get it reopened. If we don't explain why the question is unclear, how can OP clarify and improve their question?
If a previous close-voter has already commented in such a way, and that is also our reasoning, we can of course merely upvote that comment along with the vote.
Voting to close as unclear without explaining why or requesting clarification comes off as a bit impolite, IMO. This applies even when voting to close the questions of old-timers. However, I think it's especially true if OP is new to the community.
Such comments also enable OP to ping us, saying "I've clarified now, can you review and perhaps retract the vote?" Thus, it encourages improvement and increases the overall quality and activity on the site.
As Mark Mayo put it in another post:
If you're voting to close, welcome them to the site, and explain why you've voted for their question to be closed. It's very discouraging for a new user to come on here, ask a question, and just get it closed off with no feedback. Always leave a comment if you think it'll help.
To clarify, this post is only about voting to close as unclear. I often VTC as duplicate, off-topic and too broad without leaving comments because those closures often explain themselves. (Through the notices, etc.) However, I feel that when VTC as unclear, a comment is quite crucial because otherwise it's difficult for OP to clarify. They need to know why it's unclear before they can clarify.
Of course, it doesn't have to be a long comment. A single explanatory sentence or question will typically do.