'Cognitive component' is a socio-psychological term used to describe a person's belief or knowledge about something. It is one of the three types of 'attitudes'.
The other two are:
Affective component: Someone's emotions or feelings towards something.
Behavioral/conative component: The way someone's attitude affects the way they choose to behave or react.
What is the cognitive component?
The best way to describe the cognitive component of attitude is to use an example.