There are two main sections to Job 15. The essential message of verses 2-16 is: "Job, you are evil." The essential message of verses 17-35 is "Job, God punishes evil people."
The first section, verses 2-16, is comprised of three stanzas of five verses each:
A. (2-6) "Job, your foolish talk is irreverent toward God."
B. (7-11) "Proud Job, we know just as much as you."
C. (12-16) "Job, you are evil."
The second section, verses 17-35, is built around two five-verse stanzas:
A. (20-24) "The wicked man is in anguish in this life" (present tense).
B. (29-33) "The wicked man will suffer loss" (future tense).
(both of these stanzas contain the Hebrew verb for believe/trust in their central verse -- verses 22 and 31)
The second section includes some other components as well:
Verses 17-19 introduce the second section of the chapter.
There are 2 two-verse stanzas in the middle of this section (25-26 and 27-28). Notice that they both begin with the word "because" in the ESV.
This section is closed out by two proverbs (34-35), which both use pregnancy and childbearing as a metaphor. These proverbs are distinct in that, unlike the preceding verses, they describe a plural group of evildoers, not an individual evil man.
What does it all mean? Well, the above is a teaser, asking you to listen to this Sunday's sermon!