Labels allow administrators to group related objects, such as VMs, and then apply policies to those labels, rather than having to manually apply the policy to each individual VM. This is the most efficient way for an administrator to apply a security policy to dozens of VMs. Reference: https://portal.nutanix.com/page/documents/details?targetId=Platform-Administrator-Guide-v5_7:pag-sec-category-label-c.html

When uploading images from a local workstation to Prism Central, the destination cluster is determined based on the alphabetical order of the cluster names. Specifically, the first available cluster in alphabetical order is selected as the destination for the image upload.
This behavior is documented in the Prism Central Admin Guide, which states that when you upload an image to Prism Central, "the image is stored in the first cluster that has sufficient space and starts with the letter that appears first in the image name."

From Prism Central's main dashboard page, an administrator can access any cluster by clicking the cluster quick access link. This will open the cluster summary page, which contains detailed information about the cluster, including the nodes, virtual machines, and applications running on the cluster. Reference: https://portal.nutanix.com/page/documents/details?targetId=Platform-Administrator-Guide-v5_7:pag-prism-central-cluster-access-c.html