Not too long ago Google announced better rankings for mobile-friendly websites and cast a dark shadow on those sites that were not “mobile-friendly.”
Why would Google care? Because more and more people are using Google from their smartphones and tablet devices.
If your website is not mobile-friendly Google isn’t going to remove your website from their index/database, but they may not show it on a search engine results page (SERP) for someone searching Google from a smartphone or tablet.
You can test your website using the Google mobile-friendly test page at this link: https://google.com/