Glass, thorns and other small incursions to your tubeless tyre will generally self-seal. Large cuts to your sidewall mean whipping out a spare tube. In-between sized holes and cuts causing slow leaks can be quickly repaired with a tyre plug. An essential time saver for tubeless mountain biking.
Bought one of these repair kits from GE. Looks to be the business. You have a plug preloaded on the handy carry tube, so you are ready to shove it in any unfortunate hole in your tyre (that is too big to seal up with liquid tyre sealant) and that's it, job done! Ride on!
This is a truly magic product. Since buying I haven't had a single flat of any kind.