For UC Berkeley students, if the course meets the relevant criteria, it will fulfill a requirement. For example, any Reading and Composition courses you take in the summer will fulfill your Reading and Composition requirement. The class information in the Academic Guide will indicate which requirements a course fulfills.
For non-UC Berkeley students, your home institution determines if courses you take at Berkeley Summer Sessions transfer for credit or fulfill a requirement. You can disregard the information under "Requirements this class fulfills" in the Academic Guide.