It is a concept created by Durkheim

It is a concept created by Durkheim.
It means something similar to social causes.
E.g. Durkheim studied about Suicide (1897). He said that if he could link such individual behavior of suicide to social facts (social causes), he can make a case of sociology.
Here he did not studied the individual reason, but was rather interested in the different causes and suicide rate among groups, regions, countries, and different categories of people (e.g. married and single).
For him, it was the nature of social facts that led to differences in suicide rates.