The GMAT exam measures higher-order reasoning skills. You’ll need basic English-language and math skills. However, the test measures your ability to reason with these skills. All sections of the test, including the AWA and Integrated Reasoning sections, involve reasoning. “Higher-order” reasoning skills involve complex judgments and include critical thinking, analysis, and problem-solving.
The GMAT exam basically measures your analytical skills.
The Analytical Writting Assessment analyzes the reasoning behind an argument and how you respond in your writting.
Integrated Reasoning section wants you to interpret and synthesize information from different sources and in different ways.
The quantitative section wants you to reason quantitatively on the basis of your knowledge in arithmetic, algebra and geometry.
The verbal section expects you to read and thouroughly comprehend written material and to do reasoning and evaluation of different arguments.