If you want to re-format an external hard drive (a drive you plug into your computer, instead of installing inside of your computer) or flash drive, it's extremely easy to do.

How to Format SSD on a MacBook. A Solid State Drive is primarily used on laptops and other lightweight devices, as its compact size proves adequate for such portable hardware units.

While the Mac can use a hard drive formatted for Windows, some features may be limited. So it's a good idea to format a new hard drive specifically for macOS.