UUIDs are 128bit Hexadecimal valued text known as Universal Unique Identifier that are familiar with tech geeks and App developers. All the hardwares/devices like Laptops, Hard disks, have a unique UUID number. MAC computer also have a UUID for the entire assembly.
How to find Mac UUID
Finding your Mac’s UUID. Go to Apple Menu and click on “About This Mac” , Then open “More Info…” Then click on “System Report…” and select “Hardware” on the left side and on the right side yo can see your Mac’s or Macbook’s UUID. (You can also find Mac serial number also from there)
Find Partition UUID & Hard drive UUID in Mac
Find your hard drive’s or External hard disk’s UUIDs using a command. Open “Terminal” application and run the below command (Use your own Disk LABEL)
diskutil info /Volumes/Untitled | grep UUID
Volume UUID: 45125EB1-E1C4-3D21-9884-62DE22FBB0E9
More about UUID : Wikipedia