Job interrupts Bildad with sarcasm. How helpful his friends have been, he says, to a powerless one like himself! What good advice they’ve given him!
Bildad doesn’t get a chance to finish his speech because Job cuts him short, beginning his own speech which will last for the next several chapters. Job is out of patience, so he sarcastically complains that his friends have done him no good all this time. Instead of grieving with him in his suffering, they’ve made his pain more intolerable by blaming Job for his own suffering. Such an approach, while it might sometimes contain truth (i.e., sometimes people are responsible for their suffering) does nothing to actually help those who are in trouble.
The shades (the dead) and the waters beneath the earth tremble. Sheol is plainly visible to God, who “hangs the earth upon nothing,” collects water in the clouds, and establishes a boundary between light and dark. He makes the pillars of heaven shake, and he stills the sea with his power. He “pierces the fleeing serpent.” Job describes these things as just “the outskirts” of God’s ways, as no one can understand “the thunder of his power.”
Job goes on to describe some of the mysteries of God’s ways. God is responsible for holding together the entire visible universe, and he even sees the dead. By listing these things, Job underlines his argument that his friends don’t really understand God’s ways whatsoever and should be much less confident in their claims. His reference to the seas and the “serpent” evoke the idea, common in ancient Near Eastern writings, of subduing cosmic chaos and creating order.