This command is only available in History Free Mode. From the feature-based modeling (chapter 4.2.5 "Enumerative Features - Pattern Feature") you already know the Pattern Feature, which works similarly.
The difference between these functions is that NX may not recognize some elements of unknown bodies as a feature. Therefore, the Pattern Face 
function is particularly useful in Synchronous Modelingbecause it allows you to select multiple faces that can be copied multiple times and placed in a rectangular or ring pattern.