Hi @mrayubzada,
I’m not Laz but I can try to explain it to you quickly.
The Term Non-broadcast multi access (in short NBMA) refers to a network in which neither Broadcast nor Multicast is Supported.
Like Rene explained in the beginning of this Lesson Frame-Relay is an example as it just mimics broadcast and multicast traffic by sending a copy of the original frame from the originating PVC to all other PVCs.
Best regards,
Marcel