A Spatial Social Network (SSN) is a set of nodes and edges where nodes are geolocated to a meaningful location, that is, an anthrospace, and geographic edges connect the nodes. Edge locations specify the conceptual geographic path of information transfer, and difficulty of face-to-face meeting. In a SSN, distance between nodes can be measured as network distance or geographic distance.
This entry from the Geographic Information Science & Technology Body of Knowledge introduces the concept of a social network (SN), describes their spatial properties, and explains how to embed them into GIS.
This chapter from the Handbook of Spatial Analysis in the Social Sciences provides further explanation of SSNs and their applications in research.

A geolocated social network of households in the Amazon where edges represent hosting one another at the home (courtesy of Paul Hooper) is divided into three modules. The households are then mapped atop a spatial image of the study area to show that nearer households tend to be in the same modules (from Andris, 2016).
SSN Visualizations
Take a look at these visualizations of Spatial Social Networks! Click on the images below to learn more.

Social network analysis of nonprofits in disaster response: the case of Twitter during the COVID-19 pandemic in the United States
Gong, X., Peng, S., Lu, Y., Wang, S., Huang, X., and Ye, X. 2022. Social Science Computer Review, 0(0).