Laptop Questions? Ask a Laptop Technician for Answers ASAP!
I assuming using OS10 or above on your Mac, with the external hard disk plugged into the Mac, open Disk Utility, which can be accessed by searching for it in Spotlight.Select the hard drive from the left sidebar.Go to the Erase tab.In the Volume Format list, select Mac OS Extended (Journaled).Then, click Erase at the bottom to format the drive. Once complete the drive should be accessible and compatible with Mac (using HFS+ format).
Just wanted to follow up to see how you require any further assistance?