In the context of ASKfm 2.0, decentralization means that everybody can participate in the internal economy of the platform by answering questions and get rewards according to the value of their answers. There's no central hub controlling the process, no separate communities determining what's right and wrong, only direct, transparent and fair competition.
You want your question answered? Sure, set a reward and somebody will get to it! Not enough? Use the crowdfunding! There are surely some people interested in your question too, so get the community involved.
It also means that, since everything is running on the blockchain, each and every transaction works thanks to all of the participants. Funds are moved on pre-agreed conditions executed on the blockchain, and there's no third party overviewing it.