Latour's theories launched the discipline of Science and Technology Studies and forced us all to completely rethink the age old debate between objective and subjective realities.
Science and Technology Studies does not make hard scientific facts entirely a social construction. It simply makes visible the otherwise completely ignored layer of culture in their creation.
Latour's work is mostly concerned with drawing attention to the invisible structures of the modern constitution. And to question it. Though he's often read as a strong social constructivist or a postmodernist denying reality (much to his chagrin).
Latours theory of resistance is that there is no such thing as a purely social object, or a purely natural object. And almost everything is a hybrid of the two.
Argues that scientific objects are hybrid constructions of human and non human, nature and culture. The product of social systems and politics and laboratory culture.
Yet he's a realist - he believes in a reality that's "resistant" to the human understanding of the world that is socially made. Hard facts are resistant to being changed by humans cultural ideas.
Quarks will behave like quarks no matter what we name them, or what narrative stories we tell each other about them in scientific journals. They will not cease to exist in the world if humanity goes extinct tomorrow.