The Web of Science database provides access to citation information, so that researchers can see who has cited their publications (and what impact it is having), or see the relationships between works published (how research outputs are being used by other researchers in the world).
For PSYC 201, some instructors may give you an assignment that asks you to use Web of Science to lookup an author's work, and see how many times it's been cited. In order to complete this task, you need to know how to use the "Cited Reference Search."
The screenhots below show the search conducted, as well as the results. In this example, the article I was looking up has been cited 13 times.