A non broadcast network is one that uses technologies (such as Frame Relay) that do not support broadcast communication. Typically, non-broadcast technologies are not multi-access, since multi-access requires the functionality of broadcasts to operate.
So Frame Relay and other such technologies are never multi-access, like Ethernet is for example. They are based on point to point connections.
However, when you have a frame relay topology, such as this one, you may want OSPF to behave as if it is a multi access network. This is useful when we have a hub and spoke topology which mimics a multi access network without the broadcast functionality. This means that OSPF will expect to have a DR and BDR elected, but will expect us to manually configure them as well as the neighbour adjacecies.
I hope this has been helpful!