In case you have non-HTML pages on your website, like PDFs or spreadsheets, you received’t be able to apply hreflang in the on the HTML as it doesn’t exist.  Canonical URLs are made use of to stop duplicate content material and show to search engines like google which website page https://www.presta-addons-modules.com/en/seo/prestashop-seo-automatic-google-rich-snippets-json-ld-opengraph-twitter-tags-schemaorg.html