Cloud Run is a fully-managed compute platform for deploying and scaling containerized applications quickly and securely. It provides a simple developer experience: you build a container, push it to Cloud Run, and you get a HTTPS URL back. The pricing model is pay-per-use; you don't pay for idle containers.
The product is useful if you want a 'serverless' experience with full control over your programming language, runtime and system libraries.
Cloud Run is compatible with the Knative open standard. This means you can take a Cloud Run workload and move it to your own Kubernetes cluster with limited effort.