The AWA (Analytical Writing Assessment) is a two-section writing component of the GMAT (Graduate Management Admission Test), which most MBA graduate school admissions require. Each section is 30 minutes in length.
The Analysis of an Issue tests your ability to explore the complexities of an issue or opinion and--if appropriate--to take a position informed by your understanding. Both a computer and human will grade your test, and your score will range from 0 to 6.
Although it does play a role in MBA program admissions, the AWA is not as important as the other factors, such as the quantitative and verbal sections of the GMAT, as well as undergraduate institution, GPA, curriculum, extracurricular activities and business experience. The AWA exists to measure your communicative and analytical ability, but the other aforementioned components serve this purpose as well.
Admissions committees will consider the overall breadth of your application; this holds true for other graduate school admissions that require tests containing a writing component (the LSAT, MCAT, GRE, etc.).