This relates to multiple routing topologies in EIGRP. The starting topology and subset of routers and links in a network is referred to as the base topology. This is the default routing environment, any additional topologies are known as class specific topologies and are a subset of the base topology.
Each class specific topology carries an independent sent of Network Layer Reachibility Information (NLRI) this is used to maintain separate routing tables and FIB databases.
This allows the router to perform independent route calculations and forwarding for each class specific topology. Multiple topologies can be used to segment different classes of traffic such as voice, data, and video…as well as carry them over different links in the same physical network.
This is different from VRFs as they share the same IP space and are not intended to provide address conversation or reuse. EIGRP can keep these topologies segregated using the AF topology section.