It means that it is not possible at the moment to install a simple RPM.
cPanel needs rpm and yum to be working, and as part of the update process, it runs a simple test to see if it can install and uninstall a very basic RPM package. If it cannot, it stops and outputs the failure message.
rpm and yum are part of the operating system, not part of cPanel, but cPanel and EasyApache do use them, so they need to work properly. The following page explains all of the conditions, including a problem with the RPM database, that will prevent a cPanel update from succeeding: