It's a web application built by UNICEF to ease the reporting of data by its partners in the context of IP (Implementing Partner) reporting and also in the context of Cluster reporting.
PRP is an open-source project and can be found on Github.
IP and Cluster Reporting
PRP consists of two somewhat distinct user experiences targeting different but potentially overlapping use-cases. This is what is referred to as IP and Cluster Reporting. More details if you click on each of them in the left hand navigation.
Both of these sub-systems is built on top of the same data model and all the data is stored in the same database.