It means it has been designed with Kubernetes and more generally containers in minds.

That means a couple of things:

• density: we want to improve the density of the Java applications in container by reducing the memory usage;
• fast startup: we need to be able to start fast, be it for auto-scaling or for serverless workload;
• we also need to be container-friendly: this is mostly about providing the necessary tools to easily deploy in a cloud environment.

That being said, it also runs perfectly well on a physical server or on whatever you want to host it. It's just that the container world brings some additional constraints.