Page Thumbnails view
Page Thumbnails view is a sidebar on the left side of the screen that shows a thumbnail image of each page in the document. In this view, you can rearrange pages and document sections, navigate to a page by tapping its thumbnail and more.
Turn on Page Thumbnails view: Swipe right from the left side of the screen or tap in the toolbar, turn on Page Thumbnails, then tap the document to close the options.
Close Page Thumbnails view: Swipe left across the thumbnails.