Hello World Module
The aim of the Hello World module is to communicate the essence of what multi-tenancy is.
Consider a scenario where a user, let's say Alice, creates an 'instance' of the Hello World module. This can be done from the Playground. The Playground gives the users the ability to interact with the Smart Modules interactively. By the virtue of creating an 'instance', Alice becomes a tenant of the Hello World Smart Module. The instance Alice created will have its own ecosystem of data, despite using the smart contract anyone else could also be using. However, the data is completely abstracted between different users. That's the core of multi-tenancy.
Check out this video to understand multi-tenancy is greater depth.