Mobile-first indexing meaning in English
What is Mobile-first indexing?
In November 2016 Google announced that they were experimenting with a mobile-first index, meaning a stronger focus on mobile sites in algorithmic calculations.
In March 2018 Google announced they were migrating some sites that followed best practice to mobile-first indexing.
As from July 1st 2019 all new sites - meaning sites new to the web, or to Google Search Console - should now by default be on mobile-first indexing.