Optimizing for quality of user experience is key to the long-term success of any store on the web. For any store, Web Vitals can help you quantify the experience of your site and identify opportunities to improve. Similar to the Google Webmaster Tools(GWT) that helps you to evaluate and maintain your website's performance, the Core Web Vitals report shows how your pages perform based on real world usage data.
Core Web Vitals are the subset of Web Vitals that apply to all web pages, should be measured by all site owners, and will be surfaced across all Google tools. This is the user experience needs that all websites should be striving to meet. Specifically, Google identifies the core user experience needs as: loading, interactivity, and visual stability. Here’s how those user experience needs are measured.
The Core Web Vitals report is based on three metrics -LCP, FID, and CLS and it shows URL performance grouped by status, metric type, and URL group (groups of similar web pages). However, if a URL does not have a minimum amount of data to generate the report data for any of these metrics, it is omitted from the report. Once a URL has a threshold amount of data for any metric, the page status is the status of its most poorly performing metric.
In case, if you see the "No data available" screen, then it means either that your property is new in Search Console, or that there is not enough data available
As per Google, site owners can measure the quality of the user experienceof their sites with these metrics:
You can measure the Core Web Vitals using Google Search Console just by clicking on the Open Report button. The Chrome UX Report is the another way to measure Core Web Vitals. You can also run a live performance test for individual URLs using the PageSpeed Insights testing tool or the Chrome Lighthouse tool. Once you have measured your report, then you can analyze if your site needs an improvement.