Clicking on the name of a document in the document list shows a preview of the document contents:
If the document has a convertible file format then a preview in PDF format or the image itself is shown:
The right panel contains additional details about the document, including the filename, size, and owner.
The current document is downloaded using the Download file button on the top right.
Navigation is accomplished by either clicking on the folder name on the top left (breadcrumbs) above the list of files or when previewing a document by clicking on the "X" at the top right corner.
In preview mode, one of the details tabs is the document metadata. That tab shows the content type and related information defined for that particular document.