The Directory Listing page, which shows the contents within a directory, is served when a particular path is both a directory and does not have an index file within it.
Disabling The Directory Listing
To prevent showing a Directory Listing page, add an index file, such as
index.html, which will then show that file instead when accessing the directory's path.
If you were expecting a file to be here, check your Build output from the Deployment Overview from your ZEIT Dashboard.
Using advanced configuration, you can also implement a custom 404 page in place of a Directory Listing.