If Google decides that your site is not properly mobile enabled by April 21st 2015 then it will degrade your listing in Google search results on mobile devices, including tablets.
Google has been tweaking its algorithms over the last 18 months to favour mobile enabled sites for searches on mobile devices, this is entirely consistent with Google’s need to delivery the best possible results for searchers. Google wants sites to be easy to navigate & read for users on mobile devices.
It is important to note here that Google will decide if you site is mobile friendly using its own standards. You may have a site that look & operates well on mobile but it may still fail the Google mobile friendly test. You can check out your site at the following url to see if Google regards it as mobile friendly
Just add the url of the page you want to test and hit return, remember to check all key pages on your site and not just your home page as the results can vary from page to page.
Remember to add the total for mobile and tablet to get a full picture of the traffic that will be affected by this change.
As I said earlier you need to check out all the key pages on your site to ensure they are all mobile friendly , just checking the home page is not good enough. If you are unsure what pages on your site are the key pages again Google Analytics come to the rescue.
This is a good place to start in deciding what pages you need to check to see if they are mobile ready.
This is very important , do take action quickly.