Complex, multifaceted, as well as higher or highest-level means of learning.
Cognition is a form of learning that involves especially the application of past experience and knowledge to otherwise novel experiences, particularly where novel solutions are required to maximize profit or minimize costs.
Cognition is what being a biologist is all about. That is, your goal, as a biologist, is not just to be able to learn biology but to apply that biological mastery to novel systems and situations. See, e.g., biology major.