The speaker notes is a great place to jot down things you want to cover when delivering your presentation. Here’s how to show or hide the Notes pane in PowerPoint Online:
At the bottom edge of the browser window, on the right side, click Notes.
Click Notes to either show or hide your speaker notes. The size of the Notes pane can't be changed, but a vertical scroll bar will appear on the right side if the pane is filled with notes.
PowerPoint Online isn't able to print speaker notes.