Every user/requestor (a person or system that connects to PRPC) gets session memory. This session memory is called the Clipboard. A Clipboard Page is an Object in the memory space. You can create Clipboard pages by using either a Data Transform Rule or an Activity Rule. These rules have Methods that can be called like Copy or Page-New to manipulate or create Clipboard pages.
When you start a new process in PRPC, the details of the work item will be captured in the clipboard in a page named "pyWorkPage". Suppose you have created 2 properties in the work type, FirstName and LastName, the values captured from the user interface (or retrieved from external data sources) for these 2 properties will be found in the "pyWorkPage".
A Data Transform can then be invoked to concatenate the 2 properties into another property named FullName. This will also appear in the "pyWorkPage" clipboard page.
Since you have posted this question in this forum meant for "PRPC: Fast Track" course, I assume you have enrolled in the course. Please refer to the student guide on page 203 for the discussion on Clipboard and page 345 for the discussion on Data Transform.