With the cloud edition (SaaS) you run your Shopware 6 shop without having to take care of the hosting yourself: Shopware manages the entire infrastructure as well as updates and security patches. This lets you get started quickly and without technical maintenance effort, but in return you have fewer far-reaching options to intervene than with a self-hosted installation.
Further information
Please find more information regarding the cloud edition of Shopware 6 in the official Shopware documentation:
Shopware documentation: Shopware in the cloud (SaaS)