The ribbon is the band-like command interface that spans the top of the OneNote app window. Clicking a ribbon tab shows the commands available in that category. Clicking any command on the ribbon applies that command to a selection you’ve made in OneNote.
Do any of the following:
To hide the ribbon so only its tabs are shown, double-click any ribbon tab (for example, Home).
To show the ribbon again, click any ribbon tab.
Note: Some functionality in OneNote 2016 for Mac is contextual — controlled by direct interaction with certain interface or page elements. For example, the Table tab on the ribbon appears only when you have any part of an inserted table selected. You can often gain quick access to time-saving commands by Control-clicking certain elements in your notes, or by exploring the commands on the OneNote menu bar on your Mac. Either way, browsing through all parts of the OneNote interface will help you learn and take full advantage of the app’s less obvious capabilities.