Anything sociological has to do with how society works. Sociological research — like, say, a sociological study that looks at economic inequality in a country — focuses on what people are doing not as individuals but as a group,
Sociology is the study of how societies function—the way they form, what rules they follow, the way change affects them, and so on. Things that are related to sociology are sociological, and people who are particularly interested in sociological things are sociologists. They study things like the effects of technology or the role of art in a society. The Latin root of sociological is socius, "associate."