Why can't I create a directory on a mounted USB drive after mkdir, but finder new directory works?
mount without any options gives an overview of the mounted file systems with information such as the type of file systems, location, and mount options. In your case, you have one file system mounted in /Volumes called MiniPro 2 which is a HFS file system mounted noowners (ignore permissions). Your list (ls) command reveals that you also have a directory named MiniPro\ 2 in /Volumes. Once you have determined that the directory MiniPro\ 2 does not contain any files that are not backed up and you can safely remove the directory MiniPro\ 2 then remove the directory. Do this without MiniPro 2 mounted.