86box is a pc emulator that emulates the hardware of a pc, such as cpus up to a Pentium II (be warned that you need a powerful cpu to be able to get performance using a P2, so I'd suggest using closer to a pentium or older). Essentially you choose the parts of the computer you want to emulate when you create a new instance, so if you wish to recreate a computer you had in the 90s, it's possible that you can since 86box provides roms for many different computer parts, like motherboards, cpus, gpus and sound cards. Sure, this post doesn't go into depth about the emulator itself, but that doesn't mean they have to. You could've spent 5 minutes to look up the emulator itself and realize what they're talking about