The loadfile command returns a string. This string contains whatever was in the file that you loaded. Normally the command is used to load a function into a variable, but it could come in handy any time you need to load any text into OFP.
Keep in mind that functions are just strings, no different from any other. The only difference between the 'loadfile' and 'preprocessfile' commands is that 'preprocessfile' will NOT load the comments from the file (indicated by // or /* */).
So, let's say you have a dialog. You could use the ctrlsettext + loadfile commands, and display a text file to a control:
ctrlsettext [1, loadfile "stuff.txt"]
Or you could store "stuff.txt" into a variable, in case you needed to use it more than once:
_text = loadfile "stuff.txt"