Files can be displayed on wiki pages as thumbnails or links. Here are some examples. See the Confluence Display files and images page for further details.
A clickable image
Select Insert files and images and upload your image. Click on the image and select Link. Type or paste in the URL you'd like to link to. Clicking on the image below should take you to the University of York website.
Links to Google documents
You can link to Google folders, Google Docs, Google Sheets, Google Forms and more.
A link to another wiki page
A thumbnail
Insert a pdf document as a thumbnail