Ho to improve Drupal site score on PageSpeed Insights Site I have check score on PageSpeed Insights,
But I am getting following error

Should Fix:
Eliminate render-blocking JavaScript and CSS in above-the-fold content
Your page has 16 blocking script resources and 8 blocking CSS resources. This causes a delay in rendering your page.
None of the above-the-fold content on your page could be rendered without waiting for the following resources to load. Try to defer or asynchronously load blocking resources, or inline the critical portions of those resources directly in the HTML.
A possible starting point might be the Advanced CSS/JS Aggregation module.

The following article shows some possible configuration options that can increase your PageSpeed Insights score:

https://www.northstudio.com/blog/increase-your-drupal-site-pagespeed-score-part-2-advagg