FDS is Famicom Disk System.
It's a special Famicom-like (Famicom is the Japanese name of Nintendo Entertainment System) console where games are loaded from diskettes.

FDS images are different from NES images in that they are usually named .fds, not .nes, and that you also need a disk system BIOS image (usually named as disksys.rom for emulators).

Do not ask us (the author of this site or the people at the nesvideos forum) to send you ROMs or FDS images. Any such messages will be deleted.