Hybrid hard drives are a standard platter/sata with a SSD drive built into it. It acts as a cache to speed up read/writes. IMO, kinda useless with the price of actual SSD drives plummeting.
People get the hybrid drives confused all the time since SSD is in the name/model of the drive and show up in search results with the rest of the SSD drives, usually at a lower cost than a comparable size SSD.
The benefit of the hybrid drive is that it's a nice middle ground between SSDs and HDDs. You get the capacity of HDDs with a bit of the speed benefit of SSDs at a cost that affordable.
1TB SSD: $270-ish with these read/write speeds.
1TB Hybrid HDD: ~90 bucks with decent read/write speeds.
Yes, SSD costs are coming down, but for someone not wanting to buy used parts for their build/upgrade and don't have a ton of cash to work with, SSHDs aren't a bad way to go.