Page speed is “page load time” (total time to fully display the web content of a specific page from host to broswer). Now page speed will be the crucial factor for search engine rankings in google. Leading Search engine Google now make Page speed as mobile ranking factor.
All the webmasters must work to improve Time to first byte on their website. TTFB (how much time it takes for your internet browser to receive the first byte from the website web server). You can check time to first byte on webpage test website https://www.webpagetest.org
You can evaluate your page speed with Google’s PageSpeed Insights. Google recommends webmasters to use the new updated PageSpeed report available online and tools like LightHouse to measure web page speed and make improvements.
From July 2018, Google search engine crawlers will look at how fast your mobile pages are and you will get ranking accordingly. Google will use page speed as a ranking factor in mobile search. Google has been promising to look at mobile page speed and AMP will be a decisive factor for sure.