Since April 21'st Google has rolled up a new search algorithm that boost the rank of mobile friendly websites.
Because of the massive growth of the mobile devices used to browse the internet instead of the desktops, this will affect the online businesses that are not mobile ready.
If you’re not yet mobile-friendly, try to get there as soon as you can. And if you are mobile friendly, get ready for the next update – because it’s not possible to ignore mobile development and compete with the optimized sites on the same niche.
Another fact taken in consideration by the new algorithm is the loading speed of the site. Keep in mind that that does not mean that you should reduce the information on your site, if the user is in a mobile device.
Since the SEO is a very important part of your website, do not take it easily and because google is the leader on search engines, you should take it's advice.
If you are not sure if you have a fit site for mobile devices, test it on the mobile-friendly testing tool. It should also confirm that your site is mobile friendly or it will point the errors that will bring your site down on the search pages. Take in consideration that the results may be affected by the crawl time delay.
Also i suggest to create and use a Google webmasters account to make your your website is always in a good shape to get in first place on the search result pages.