It's likely because your web server does not block directory indexes by default.

For examplehttp://e-francais.com/concrete/src/Updater/Migrations/Migrations/... shows the entire contents of the directory.

You may be able do disable directory indexes by adding or editing a file with the name .htaccess (note the leading ".") and adding the words

Options -Indexes

If the file already exists,make a copy of it before editing, since it's possible to break your whole site if you get this file wrong.

You will need to use your hosting control panel to edit this file, not concrete 5.

You should also get Google to remove those URLs which you'll need to do with a Google webmaster account.