And the dockerinaction part (also called “namespace”) of the image name is basically the name of the user or organization that created the image. You can see other images from the same maker at https://hub.docker.com/u/dockerinaction.
And “namespace” is not an alternative to dockerinaction, if that’s what you think. It’s just the term often used for that prefix; see Repositories | Docker Documentation. Don’t be confused by the “docker” part in dockerinaction; it’s just the name someone is using for their Docker Hub account.