These workflow components are special in the way, that they are not converting or producing anything, but they can be used for setting up the flow of processing.
The components are:
Use this to implement a conditional workflow, which e.g. branch out depending on the contents of the input file.
Use this to create multiple outputs (branches) from a single source. If you e.g. want to create both an email, a local PDF file and a print out.
If you want to insert a special duplex page e.g. terms and conditions, then you might be able to insert that as the first or last page in your normal template, but if that is not sufficient, then you should check out this component.