If your site is not already mobile-friendly, you need to get it there before April 21st when Google has said they will start using mobile-friendliness as a ranking signal for mobile searches. The change will affect mobile searches in all languages worldwide. The announcement can be found on the Google Webmaster Central Blog … the link is HERE.
If you would like to test a few of your pages to see if they are mobile-friendly, Google has a test tool HERE.
Google did a great Q&A session that talked about and answered questions about the upcoming ranking change for mobile-friendly sites.