Google Understands Language Variations of Words as Synonyms
Google tends not to show results in a different language from the one the query is written in. For languages with different dialects, like Spanish, Google will try to understand differences as synonyms.
Only Have One Language on a Page to Ensure it Will Appear in Search
If you feature more than one language on the same page, Google may struggle to figure out what the primary language version should be and whether it should be shown for queries for either language.
Only Index Original Language Content if You Use Auto-Translate
GSC May Not Show Data For Your Other Same Language Sites if Content is Identical
Hreflang data may only appear for one of your sites in Search Console if the content is identical across a collection of same language sites e.g. UK and US. Use the ‘Inspect URL’ tool to check for issues like this.
Hreflang is Only Needed When the Wrong Language URLs Are Being Shown
If you don’t see the wrong country URLs appearing for users searching with a specific language, then it’s not necessary to add hreflang to those pages.
Hreflang Isn’t Needed for a Language Change
Hreflang is only needed for instances such as using the same language for different countries. It isn’t needed for a site which changes its language completely.
Automatically Translated Content Should Not Be Indexable
Automatically translated pages are seen as automatically generated content and shouldn’t be submitted to be indexed or be made available to users.
Restrict Language in Advanced Search to Check Language is Seen Correctly by Google
Can check a page is showing in the correct language by searching for the page and restricting the language in Advanced Search. If the page doesn’t show up then Google thinks they’re in a different language than the one you’ve set.
Use a Single Language per Page
It’s OK to have pages in different languages on the same site, but each page should only have content in a single language.