File List in Informatica is a concept where your multiple files are directly read.
Lets say there are 10 Files coming from your Source.
1) You can import the file which has max number of columns and link it to target
2) In Session properties you can pick a Indirect file approach and give the path.
Now you have to create a file at the same path where you will have all your 10 files name in it.
Finally place this file name in your session properties under file path.
Run it you will have multiple files data loaded into a single file or a table as per your requirements.
That is File List Concept.
Hope it helps you.