Correspondence Management is an important part of AEM Forms. The official Correspondence Management documentation can be found here.
The hands on exercise available as part of this article was created using AEM Forms 6.3. The hands on exercise can be used with Aem Forms 6.2 as well.(certain menu items could be different in 6.2)
The hands on exercise will walk you through the process of creating a sample correspondence.
After going through this hands on exercise you will get fair understanding of Document Fragments,Data Dictionary,Remote Functions and Batch generation of Correspondence through watched folder mechanism.