That’s all you need to know for this step.
This means that the device that the Mac/Unix system uses to communicate with the DVD drive is /dev/disk2.
In my case, the last entry is the entry for my DVD drive - which you can tell in a variety of ways, including the words external and DVD, as well as the size - and the identifier is disk2. 2: Apple_CoreStorage MacOS 499.4 GB disk0s2ģ: Apple_Boot Recovery HD 650.0 MB disk0s3