The folder capture node outputs the path to the input file in msg.payload (also msg.filename) and various other file properties in msg.file, such as the basename, name, file extension, and folder location.
This information can be utilized in Change nodes, Functions, and for operations like J expressions (JSONata).
The following image shows this information in the Debug panel.
Adding a timestamp can be done in a Function or using J expression as discussed in your other topic 
(Output Presets and filenames - #3 by TGREER)
Erik