Accelerated networking provides low network latency through Azure's in-house programmable hardware, which is based on field-programmable gate array (FPGA) and technologies such as single root I/O virtualization (SR-IOV). During Azure's software-defined networking stack movement away from CPUs and into FPGA-based SmartNICs, compute cycles are reclaimed and available again for end user applications, putting less load on the VM, decreasing jitter and inconsistency in latency.
Accelerated networking also enables customers to use more bandwidth, with up to 30 Gbps per VM.
If you are interested in SmartNICs or the next generation, SDN/SDWAN, I would highly recommend Microsoft's research around that topic at https://www.microsoft.com/en-us/research/publication/azure-accelerated-networking-smartnics-public-cloud/ as well as the session, Inside Microsoft's FPGA-Based Configurable Cloud, from Mark Russinovich at https://www.youtube.com/watch?v=v_4Ap1bjwgs.