Fix Google PageSpeed enable compression in PHP and htaccess
Enabling gzip compression on your script / webserver will not only help you achieving a greater score on Google PageSpeed "Enable compression"  test, but also allow a faster rendering time on your visitors browser.
Optimizing encoding and transfer size of text-based assets -- Web Fundamentals
Zlib compress example
The easiest way to achieve it, providing your are using PHP, is to add a few lines at the beginning of your PHP script to activate zlib output compression  and Check the GZIP compression on Google PageSpeed test:
PHP: Runtime Configuration - Manual
A good way to check if it works, is to perform a before / after test on gidnetwork (Fig 1)  for example.
GIDZipTest: Web Page Compression (Deflate / Gzip) Test - GIDNetwork
Enable compression htaccess
You can also add the following piece in your htaccess file, which will tell Apache to compress the corresponding files, providing the mod_deflate is activated on your server:
For more details on Apache compression, please see the great articles about this subject on betterexplained.com  or www.cloudtech.ch .
How To Optimize Your Site With GZIP Compression | BetterExplained
For example, this allowed me to pass the Google PageSpeed  test Enable Compression  on a website, going up from a score of 72 on mobile (Fig 2) to 89 (Fig 3), and up from 79 (Fig 4) to 89 on desktop (Fig 5).