To get started with SAP HANA Cloud you will first need to setup a BTP global account. This is the highest level of account management in BTP. Think of the global account as the 'contract' level.
SAP BTP provides different types of global accounts: enterprise and trial accounts.
A trial account lets you try out the platform for free. Access is open to everyone. Trial accounts are intended for personal exploration, and not for production use or team application development. They allow restricted use of the platform resources and services. The trial period varies depending on the environment.
An enterprise account is usually associated with one SAP customer or partner. The global account is the level at which you purchase platform resources and services.
Once you have your global account setup, you can then create one or more subaccounts which consume the services of the global account. During the creation of a subaccount, you choose the cloud provider and also the region. For example, Azure in EMEA, or AWS in APJ. This service provider location does not have to be the same as the actual location of consumption. As more cloud providers become available, the list of providers in more regions will increase.
Subaccounts are technically independent of each other. This means users, applications, authorizations etc. are not shared between subaccounts.

Subaccounts can be optionally managed using directories. Directories allow you to group subaccounts for easy management of large numbers of subaccounts. Quotas can also be assigned to directories in case you don't want to assign quotas directly to subaccounts.

A directory can be sub-divided into more directories to create a directory hierarchy. Subaccounts can be assigned to any level of the directory hierarchy.