SAP Process Observer for Built-In Processes (POB) allows organizations to monitor and optimize core processes based on SAP Business Suite’s built-in business object events. It’s been around quite a while — since 2011, I believe. The functionality it provides is somewhat close to SAP Event Management (EM), but there are major differences in functionality and also in the scope of the process that each covers. Comment below if you want more details on the differences.
Here is a set of documents that are available on SCN that will help guide you through understanding POB and how to put it in: