First of all, what is cognition? Cognition has to do with how a person understands and acts in the world. It is a set of mental processes that are part of nearly every human action. For instance, answering the telephone involves perception (hearing the ring tone), decision taking (answering or not), motor skill (lifting the receiver), language skills (listening and talking), social skills (interpreting tone of voice and interacting properly).
Cognitive abilities are supported by specific neuronal networks and brain structures. For instance memory skills rely mainly on parts of the temporal lobes and parts of the frontal lobes (behind the forehead). In the article What are Cognitive Abilities and Skills? you can find good explanation and examples, together with stimulating brain teasers to exercise the cognitive abilities described. Learn, and have fun!