With an increase in global web traffic from mobile devices & also studies showing that mobile visitors are more likely to revisit mobile-friendly sites, mobile usability has now become an imp part of search results. Mobile usability report helps identify issues affecting your pages. This can be used to fix errors & also their search performance & relevance. Most mobile browsers do not render Flash-based content. Also your pages should specify a viewport using the meta viewport tag
For the mobile friendly websites,
1) The viewing area should adjust to the device screen size
2) Content should flow in viewport
3) Scaling of the fonts
4) Buttons should be well placed & visible
5) Using mobile friendly tech for the mobile website
Six primary mobile usability errors are
1) Flash Usage
2) View Port Not configured
3) Fixed-width viewport
4) Content not sized to viewport
5) Small font size
6) Touch elements too close
Google Mobile-Friendly Test URl is https://www.google.com/webmasters/tools/mobile-friendly/. This test will analyze a URL and report if the page has a mobile-friendly design.