This is for !retrocomputing@lemmy.sdf.org . You install this in a retro PC where a physical drive would go. Your retro PC thinks your disk images are actual disks, and everything else works like it used to. It's a nice quality-of-life improvement.
Retro game consoles have been doing this for a while. The Sega Dreamcast's GD-ROM drive is prone to failure, so modders replace it with hardware that loads disk images. I haven't heard of this for retro PCs before, but it makes sense.