Hosted organizations - tenants, active directory organizational units which store customer's users, security groups, contacts etc.
Hosted organization quotas explanation:
Organizations - Amount of allowed hosted organizations.
Users per Organization - Amount of users allowed per hosted organization.
Domains per Organization - Limits number of domains allowed per hosted organization.
Allow to Change UserPrincipalName - Enable to let customer change UPN for hosted organization users.
Security Groups per Organization - Amount of security groups allowed per hosted organization.
Locations per Organization - Allow customer to manage locations. Useful when organization is big and distributed across countries. Customer can create multiple locations and mass-apply to users. Location includes information like country, city, address, phone etc.
Devices per Organization - Amount of devices allowed per hosted organization.
Deleted Users per Organization - Amount of deleted users alloewd per hosted organization.
Deleted Users Backup Storage Space per Organization, Mb - Amount of space allowed for deleted users backup storage, in megabytes.
Force Save as Deleted User on Deletion - Enabling this option will force each deleted user to be backed up to Deleted Users.