Hreflang attributes may not help you increase traffic; instead, the goal of using them is to serve the right content to the right users.
They help search engines swap the correct version of the page into the SERP based on a user’s location and language preferences. For information on how geotargeting can help with rankings, learn about ccTLDs.
The difference between hreflang and canonicalization
Canonicalization is a tool for showing search engines which version of a URL (each with the same content) is the dominant one to avoid duplicate content issues. Hreflang, on the other hand, is a tool to show which of the different (but often similar) pages (based on language or region) should show up in a search.
Google recommends not using rel=”canonical” across country or language versions of your site. But you can use it within a country or language version.