A modern Ethernet chipset has a large number of independent hardware queues. These can be assigned to VMs for direct access to the NIC, bypassing the hypervisor. AWS, since you used that example, offers instances with this type of direct bypass.

Just to pull an example from memory, the ubiquitous Intel 82599 10GbE NIC silicon has up to 128 TX and RX queues in hardware. IIRC, these are bundled in pairs for direct access in virtualized environments, so in principle you could have 64 virtual cores each with their own dedicated physical hardware queue. This is almost certainly what they were talking about. That is the whole point of this feature in Ethernet silicon; it gives cores (virtual or physical) dedicate network hardware off a single NIC.