Google has publicly stated in April they are releasing a update specifically targeting mobile search. It is rare for Google to give such advanced warning they stated;
“Starting April 21, we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results.”
You need to go here and run your site; https://www.google.com/webmasters/tools/mobile-friendly/
If you want to test a few pages, you can use the Mobile-Friendly Test. If you have a site, you can use your Webmaster Tools account to get a full list of mobile usability issues across your site using the Mobile Usability Report.
Go to your web analytics and get clear on how much traffic comes to you site from mobile. Everyone is using mobile devices, since i got my Phablet iPhone6 last year i have am using it a lot more myself.
Other tools you can use;
If you are not tech inclined then get someone who knows about this to do review and make recommendations.
Google’s John Mueller announcing this;
The full video with key info right at the start; https://www.youtube.com/watch?v=vfSFcImNFX4#t=25