Ecclesiastes begins with the striking phrase “Vanity of vanities … All is vanity.” The ESV provides a helpful footnote on “vanity” in 1:2: “The Hebrew term hebel, translated vanity or vain, refers concretely to a ‘mist,’ ‘vapor,’ or ‘mere breath,’ and metaphorically to something that is fleeting or elusive (with different nuances depending on the context). It appears five times in this verse and in 29 other verses in Ecclesiastes.”
I think the idea of something that is fleeting is more helpful to me in reading Ecclesiastes than some other modern language attempts.
- “Meaningless, meaningless … Everything is meaningless!” NIV
- “Absolutely pointless! Everything is pointless.” GW
- “Everything is nonsense … nothing makes sense!” CEV
- “Life is useless, all useless.” GNB
I’ve suggested to people who struggled with reading Ecclesiastes that it might be helpful to substitute their translation’s rendering of hebel with vapor or fleeting, and some have found this helpful.
In Ecclesiastes 2:14-16, the fleeting nature of life is observed in the contrast of the wise and the fool. Clearly, being wise is better than being a fool. Wisdom is said to mean that you have your eyes in your head, which is probably a way of saying the wise can see where they are going. In contrast, the fool is walking in the dark. Yet the tension of the book is this: “How the wise dies just like the fool!” (Ecclesiastes 2:16, ESV)
The fleeting nature of life is observed in work (Ecclesiastes 2:18-19). A person with wisdom may work very hard to accomplish something that will last beyond his or her lifetime. But Ecclesiastes sees this as a vexing problem, because the heir didn’t toil for it but merely inherits it. And it is possible that the one who inherits the fruit of someone’s labor will turn out to be foolish.
Yet some of the pessimism of the book involves looking at life from the vantage point of “under the sun.” This phrase occurs twenty-eight times in the book. It is looking at life from the vantage point of this physical life. It is the contrast of the land of the living with the realm of the dead.
Life is fleeting, and the brevity of life brings to us many vexations. But the book ends by pointing us to the one who is eternal.
The end of the matter; all has been heard. Fear God and keep his commandments, for this is the whole duty of man. For God will bring every deed into judgment, with every secret thing, whether good or evil. (Ecclesiastes 12:13–14, ESV)
while today 
Yes; “temporary” does seem to be the main meaning of hvl in Eccl. There is some pessimism in the book, but “this too shall pass” can also be very comforting.