Files can be displayed on wiki pages as thumbnails or links. Here are some examples. See the Confluence Display files and images page and the Confluence Links page for further details.
A link to another wiki page
A link to another wiki page
Links to Google documents
You can link to Google folders, Google Docs, Google Sheets, Google Forms and more.
A link to a web page
Simply highlight the text you want to link, then select Insert link then Web link, and type or paste in the URL of the linked web page.
A thumbnail
Insert a pdf document as a thumbnail