Fragment lets the Digimon survive deletion by trashing the listed number of its own digivolution cards. Every card under the stack is a hit point, which is why Fragment decks lean on Training and other stacking effects to keep the buffer full. Your opponent has to remove it several times over, and each attempt costs them more than it costs you.
16-37-1. <Fragment> is a keyword effect. When a Digimon with this effect would be deleted, by choosing and trashing the specified number of this Digimon's digivolution cards, it isn't deleted. The effect is indicated on cards by icons such as <Fragment (3)>. 16-37-2. <Fragment> is an immediate-type effect that triggers when the Digimon with this effect would be deleted. (For details, refer to 15-8-5 "Immediate-Type Effects") 16-37-3. The processing from <Fragment> for choosing and trashing the specified number of this Digimon's digivolution cards is optional. If the content of that condition is executed, the processing for "prevents the deletion" will be mandatory.
Comprehensive Rules §16-37 — official rules page
12 cards carry this keyword:
Rule text © Bandai, quoted from the official Comprehensive Rules for reference. Combalo is not affiliated with Bandai.
