What is the purpose of the env vars being set in the README.md example

[MarkCallow]

I'm new to this Action and am struggling to understand the purpose of

    environment:
      name: pypi
      url: https://pypi.org/p/<your-pypi-project-name>

used in the publishing flow example in README.md and the exhortation to change name if publishing to a different repository. These environment variables are not used anywhere else in the example.

What are they for?

[webknjaz]

These are not environment variables, but GitHub Environments. It's a concept the platform has for describing where things are being deployed to.
The URL is shown on GH UI in various places. The name is just an identifier.
The environments can be automatically created on the first use or through the repository settings. There, in the settings, it's possible to apply various protection rules or scope secrets. I normally recommend setting up required reviews and a cool down timer there — this pauses the workflow right before starting the job that needs said environment and awaits for you to click on the button allowing it to run. When this happens, you also get an email notification.
Another use, security-wise, is that when you use secretless publishing, PyPI matches the environment with the trusted connection set up on its side.
Please, check out the PyPUG guide for more pointers.

P.S. Don't change the name — it's used in other guides, and we use testpypi in examples publishing to TestPyPI.

[MarkCallow]

Thank you @webknjaz. When I wrote about environment variables, I was confusing env: and environment:.

Where is the PyPUG guide? Where is it linked from? Is it https://packaging.python.org/en/latest/guides/publishing-package-distribution-releases-using-github-actions-ci-cd-workflows/?

[webknjaz]

Yes, that's the one! It's linked from the readme in some places.