Just a Primary Hard drive is all you need. Your Operating System and all application software and data can be put there. A Data hard drive is just a second drive that does NOT have the Operating System on it, but can have anything else, in case you need more storage space.
SSD stands for Solid State Drive. It is a device made from all solid state memory just like RAM, but set up in a container with some smarts and connectors so it installs and behaves just like a hard drive. Its advantage is that it is VERY fast because it does not have any rotating mechanical parts to wait for. But it is VERY expensive per GB, and you can't get huge ones like hard drives. Some people who want really fast performance (gamers among these) use HDD's to install their Operating System and several key applications (like games and their data), but there's a real limit on how many games you can load onto an SSD unit with a fixed size.
Among Gamers, some people promote use of RAID0 arrays of hard drives (usually 2) for faster performance. These days, individual hard drives are almost as fast as a RAID0 pair, but an SSD is MUCH faster than that. RAID0 has one big potential drawback - if one of the pair of drives in the array fails, you lose EVERYTHING on that RAID0 array. If you don't have a very recent backup, you have a long task to re-load everything after you replace the failed drive, and you will not be able to re-create some things.