When you start up Excel or other Office programs, they often stick a “Task Pane” up on the right, usually with the “Getting Started” heading. Annoying, isn’t it?
Switch it off one time with Ctrl+F1.
Switch it off permanently by following these steps (which you have to repeat for Excel, Word, PowerPoint, etc.): Hit Alt+T to open the Tools menu, O to select the Options command, then deselect the “Startup Task Pane” checkbox using Alt plus whatever is the underlined letter (which is different in different programs — nice consistency there, Microsoft), then press Enter for OK.