This is a kind of technical term, that it is used a lot in IT. Sometimes it is difficult to explain what RAID is, and why you should use it.
Spiceworks has a great video, only 4 minutes long that explains how RAID works, and even non IT people can understand it.
Note: RAID does not refer to the bug spray, but to a storage technology used in business usually. Even SMB (Small Business) should use RAID.
Another thing to note, is that for a ton of technical reasons I use RAID 10 (or RAID 1+0, or RAID 01). Worst case scenario I would use RAID 1 (when 10 is not supported).
The article One Big RAID 10: The new standard in server storage it talks about the approach to RAID 10 and why it should be used
But the main thing that you should know, is that I actually have had to restored broken RAID 5 arrays, and I have seen 2 RAID 5 array die during re-build (when replacing a damaged drive)