The 'Joomla! Template JSN Cube Customization Manual' provides detailed instructions on customizing the JSN Cube template for Joomla, covering topics such as CSS modifications, graphic customizations, and template translations. Key sections include tools required for editing, explanations of CSS files, and step-by-step guides for specific customizations like changing website titles and icon usage. This manual is designed to assist users in tailoring the JSN Cube template to better suit their website needs.