The intl extension is compiled in PHP, but it's not enabled by default. To enable it, you just need to make a small addition to your phprc file.
Error you may see if this is not installed
If this extension is missing, your site may throw different errors. Here is one error that may appear in WordPress.
Fatal error: Uncaught Error: Class 'NumberFormatter' not found
The DreamHost phprc file
The standard term for a PHP configuration file is php.ini. However, DreamHost uses the term "phprc" file instead. This acts the same way – only the name is different. In this article, only the term phprc is used.
View the following articles for instructions on how to create a phprc file.
If the file already exists, view the following articles for instructions on how to update it (depending on if you're using an FTP client or SSH):
Enabling the intl extension
Add the following line to your phprc file.
Kill off all running php processes
Make sure to kill running php processes to ensure your new settings take effect.
Confirming your changes
After you've edited the file and killed off all PHP processes, check to confirm the extension has been enabled. You can do this by creating a phpinfo.php file. You should see the following:
If you do not see your changes have updated, try killing off your PHP processes again: