This is Amazon EC2 traffic that moves between AZs but stays
within the same region. If it doesn’t have the source, then it defaults to
us-east. It includes InterZone-In/Out, LoadBalancing, LoadBalancing–PublicIP-In/Out, PublicIP-In/Out,
VpcEndpoint, and VPCPeering-In/Out.
Source.
Still can't understand...
What is AZs? Would you mind to answer without shortforms?