The presenter may have written on a piece of paper questions for the guest, names and patronymics of guests, notes - that is, something that may be useful during the broadcast. And there is always a full printout of the text that goes on the prompter - so that sometimes the eyes rest from the prompter, or to re-read the text of the next news during the commercial break and not stumble over the complicated name of the Arab dictator.
Another reason is the need to keep your hands busy so that they do not dangle around and look professional enough at the same time ..
Sometimes the teleprompter starts to "freak", well, or completely stops working, for such cases they hold the papers. Well, or something is not visible for example. In short, just in case.