I would say the main things are to set the scene and to show an awareness of the main literature and the key players in the area and to begin to identify the areas which you consider need further attention and why and how you are going to set out addressing them. Sometimes Universities ask for a proposed timetable at this stage so maybe helpful to check if that is the case, if so demonstrate that you have a realistic idea of amount of time needed for each stage of the research process. Hope that helps a little...