Niko Neugebauer explains the concept of Closeness Centrality:
The real center of the network or also known as The King of the Network, Closeness Centrality is a measure which represents the relative location of the Vertice to the center of the network, or better to say the average distance to all other Vertices within that network.
This measure results in the high effectiveness of information spreading/flow within the given network, because of the necessary number of Edges to cross to reach to any given connected Vertice.
Read on to see why this is useful and how you can calculate it in SQL Server 2019.