The keyword in bold is the next up in sequence that you need to insert: SelectedDate.
It's identified for you as a Date, i.e., not a number or string, and you get a sample valid value. Once you enter it, the next term will appear in bold, offering you the next keyword, with its datatype and a sample valid value. And on you go, one keyword at time. If you look at the keyword, and decide not to use it, entering a comma moves to the next one.
In fact, I would go so far as to suggest that you actually have shown condensed documentation for Calendarform.GetDate and that is useful information in itself. On the other hand, the line above it, with three placeholder commas, tells you nothing about what would go in those places.