After generating Source Code, When App.sln file is run, in solution explorer, you can see the folders created by Kushal while source code is generated. The Expression folder contains form code along with expressions code written in Kushal for each form. Each form will have one class in expression folder and each class is treated as partial class of the individual form.
Kushal folder contains Kushal Helper Classes.
References contains added References like dlls, and others.
Custom classes which you assign, will be in Kushal\Custom Classes folder.
Resources contains images and icons.
Report Folder contains added RDL and Excel template files.