Render is a cloud hosting platform made by Render Inc.: it runs a customer's applications on its own servers, so the customer does not operate machines. It hosts web services, static sites, private services, background workers, cron jobs (tasks that run on a schedule), Postgres databases and Redis-compatible key-value stores.
A developer connects a Git repository. Render builds the code with a native runtime (Node, Python, Go, Rust, Ruby or Elixir) or from a Docker container, deploys it, and handles networking, rollbacks and monitoring. Every pull request can get a preview copy of the whole application. Services scale with load, reach each other over a private network, and the full setup can be written and versioned in one YAML file (infrastructure as code).
Render is a hosted service. A workspace plan (Hobby costs nothing; Pro and Scale have a monthly fee) is paid plus compute: each service instance has a monthly price set by its memory and CPU, and small free instances exist with limits.