CFC is a Cold Fusion Component, also known as a User Defined Function, and you can either create your own, or find them available for download (some free, some require a fee.)
Typically, you would create a folder within the root of your site/application called "components" and set a mapping to that location within your application.cfc. Then, whenever you need to call that CFC, there are several ways to access functions within the CFC. My favourite is to:
<cfset queryObj = new components.myCFC().myFunction() /> <cfoutput query = "queryObj"> ... your output code here... </cfoutput>
That is CFC in a nutshell.