FIRES stands for Fediverse Intelligence Recommendations and Replication Endpoint Server; The name is a bit of a pun, in that moderation is usually about dealing with little fires continuously.
The model I've used is that we'd have data providers and software to help manage moderation recommendations and advisories, and software to integrate those into existing Fediverse software.
The API is designed to allow easy periodic synchronisation of data, specifically handling retractions.