Critical Reasoning is all about logic, assumptions, and reasoning. In short, it's the part of the exam that really makes you think critically. It's the most math-like section of the verbal section because of this logic component.
You will be presented with a short paragraph of text information. Then you will see a question prompt below that. Some questions you might see include: "Which of the following, if true, most supports the author's viewpoint?"
Or "which of the following, if true, best presents a rebuttal to the original criticism.."
Or you might see boldfaced portions of the question and get asked what role those two boldfaced portions play. Is one a conclusion and another supporting evidence? Or does one challenge a commonly held belief while the other demonstrates the opposing argument? Or is it the other way around?
All of this is in the Verbal: Critical Reasoning section. Watch out!