When you want to deploy something in the cloud you probably need tools like Terraform, Kubernetes, CI pipelines, the AWS CLI...
Backstage is a platform that unifies all your infrastructure tooling, services, documentation with a single UI.
It gives you an uniform overview of all your services. It also lets you create easily new ressources such as a new backend service.
Backstage was created by Spotify but is now hosted by the Cloud Native Computing Foundation (CNCF) as a Sandbox level project.