The functionality of your X-Cart 5 store can expand by installing add-ons (modules).
Every X-Cart edition has a different set of addons installed and enabled out-of-the-box. You can view the list on the Installed Add-ons page of your X-Cart App Store (available via the My add-ons section of your store Admin area). You can enable, disable and even delete add-ons there according to your needs.
X-Cart App Store is separated from the rest of the store to ensure that the installation, upgrade or deletion of new or existing add-ons can be safely rolled back in case of any malfunctions in your store.
Basically, since X-Cart core functionality extends via the installation of a respective add-on, the overall management consists of the addons installation, activation, set-up, deactivation and deletion.