An overabundance of men in a population has financial consequences
Quite simply, cognition refers to thinking. There are the obvious applications of conscious reasoning—doing taxes, playing chess, deconstructing Macbeth—but thought takes many subtler forms, such as interpreting sensory input, guiding physical actions, and empathizing with others.
A bias is a tendency. Most biases—like preferring to eat food instead of paper clips—are helpful. But cognitive shortcuts can cause problems when we're not aware of them and we apply them inappropriately, leading to rash decisions or discriminatory practices.