Best External hard drive for mac book pro laptop 210

You can use literally any external hard disk drive, but if you don't know where to begin shop for one at OWC / MacSales. Their prices are good, but most importantly they support Macs exclusively.

Be sure to format it (erase it) before using it. Most hard disk drives are perfectly ok. One manufacturer is not necessarily any better or worse than any other, but many manufacturers are fond of bundling various "free" apps on them. Those apps should not be used. Erasing the disk accomplishes two things: it prepares the disk for use with a Mac, and it gets rid of that potentially problematic software.

Refer to Erase and reformat a storage device in Disk Utility on Mac - Apple Support.

One further thought. Solid State Drives (SSDs) are faster but they cost more. If you are only going to use the drive for storage without an operating system on it, a mechanical drive should be sufficient for your needs.