WordPress 5.6 is packed with 85 enhancements and feature requests and over 200 bug fixes.
WordPress 5.6 brings a lot of changes for both developers and site editors alike. A new theme is now available: Twenty-One and is AAA-ready. There are also a number of block editor changes which promise to make post complex layouts easier for anyone who is using the Gutenberg editor.
WordPress 5.6 is also PHP 8 ready (make sure your plugins/custom themes are before upgrading to PHP 8) and jQuery also gets an upgrade too. All sorts of other fun things are in this update too for developers like the new REST API authentication with Application Passwords, Block API version 2, and a number of other items. Make sure you spend some time going through everything.
You can read more by looking at the release notes: https://make.wordpress.org/core/2020/11/20/wordpress-5-6-field-guide/
You can also see a complete list of changes: https://core.trac.wordpress.org/query?status=closed&resolution=fixed&milestone=5.6&order=priority
If you have not done so already – download the update or simply use your existing installation of WordPress to update your site. Either way – this is an excellent time to make a backup copy of your site(s) before upgrading.