intro-to-docker | opinionated introduction to using Docker | Continuous Deployment library

I'm reading a document from Microsoft that states about Docker volumes

Volumes are stored within directories on the host filesystem. Docker will mount and manage the volumes in the container. Once mounted, these volumes are isolated from the host machine.

Multiple containers can simultaneously use the same volumes. Volumes also don't get removed automatically when a container stops using the volume.

In our example, we can create a directory on our container host and mount this volume into the container when we create the tracking portal container. When our tracking portal logs data, we can access this information via the container host's filesystem. We'll have access to this log file even if our container is removed.

I'm confused as I understand that the volumes are isolated from the host machine, but how can that be if we can access to the data via the host.