“frustration.” The Hebrew word is kaas (#03708 כַּעַס), and it can mean sorrow, anger, vexation, grief, frustration, etc., depending on the context (it is “frustration” in Ecclesiastes 1:3; “sorrow” in Ecclesiastes 7:3 and “anger” in Ecclesiastes 7:9). Although the REV has “frustration,” more than one meaning fits well here, including “anger,” “vexation,” “sorrow,” “anxiety,” etc., and the English versions differ widely. This is a good example of how the student of the Bible must be aware that the English translation is often only one choice among a number of “good choices,” and why the Bible must be read and discussed with different possible meanings in mind.
“dawn of life.” The word “dawn” might also be “black” depending on the Hebrew root it is derived from. Everet Fox takes this to mean the blackness of hair, versus the grey hair of the old men. But the translation “dawn” occurs a number of times in the Bible. Both words, “youth” and “dawn” (or “black”) occur in Psalm 110:3.
“pointless.” See commentary on Ecclesiastes 1:2. Here we see the meaning of “temporary” coming more to the front, as in Ecclesiastes 11:8, but the primary meaning still is “pointless.”