Access Control is defined on folder level. The rights given for a folder are the rights for all items in that folder. The folder itself has no access restrictions. The content of a folder is defined by the accessable items recursive below that folder.
Example: If a user has only read access to the folder "bar" below the folder "foo", but not to "foo", he will see the folder "bar" inside the folder "foo" and all items in "foo/bar", but not the items in the folder "foo".