The TODAY function has no arguments.
The TODAY function is unusual; it's one of the few Excel functions that doesn't require any argument, although it does require opening and closing parentheses: =TODAY()
TODAY inserts the current date, which is updated each time a workbook is opened or recalculated.
Just for fun, you could use the TODAY function to find out from today's date how many days old you are. You'll see how to do that calculation in the practice session.