It depends what type of volume you use. Docker commes with a default volume plugin that allows to use cifs/nfs remote shares or local folders. Others allow to use block devices, cloud native storage or whatever…
Depending on the volume plugin, a volume can be mounted to only a single container (the block device kind), others like nfs/cifs remote shares or local folders can be bount to many containers.
Usualy a volume plugin mounts a resource into /var/lib/docker/{volumename}/ and when it’s used in a container, under the hood it uses mount --bind src dst to make the folder accessible inside the container.