According to the Nutanix Support & Insights web search result3, advertised capacity is an advanced container setting that allows the administrator to reserve an advertised storage space for a storage container. An advertised capacity setting gives the hypervisor a maximum storage size that the storage container can use.
This setting can be any arbitrary value greater than or equal to the resiliency required. The hypervisor ensures that the storage container storage doesn't go beyond the advertised capacity. If the administrator wants a container to be displayed and limited to 1TB in the hypervisor, they should set the advertised capacity to 1TB.