It's N2O or Nitrous Oxide.
NOS is a brand of Kit.
I recommend nothing but a wet kit, I like NX and have a Proton Kit from them.
Always use a window switch and wide open throttle switch.
Make sure you watch the tuning and timing. I recommend Trifecta (Talk to Vince).
Get a Wideband AFR Gauge and use it.
Finally, I would think about a direct port if you have the means.
Do your research and you'll be fine. Good Luck.