Multilingual SEO is an important aspect of your localization strategy. Not only do you want the search engines to find and index your content in your source language, but you also want to get the target language versions of your pages indexed as well, and you want your end-users to be able to search for your content in their native language!
Using the new SEO Settings Page in your Project Settings can help get you another step closer to your goal.
By providing a unique URL for each of your target languages, Localize will automatically add HREFLANG annotations to all of the pages on your website. Search engines use HREFLANG annotations to serve the correct language or regional URL in search results.
Read more here on how to get this set up for your website.