Scoot is a low-cost carrier with an all-economy layout, differentiated through paid seat selection (front rows / extra-legroom), paid meals and baggage bundles.
The LCC logic is pay-for-what-you-need: add a baggage bundle if you have bags, buy a front-row seat for comfort — bundles are usually cheaper than buying items separately.
On loyalty: KrisFlyer (shared with SIA) members accrue miles by cabin, and elite tiers add seat, baggage and lounge benefits — worth joining if you fly Scoot often.