As Flint explains (p. 43), there is an intellectual debate within the social sciences around the ideas of structure and agency. The textbook discusses some foundational definitions of agency and structure (pp. 43-44). If you need a refresher, please do re-read that section. Also, as a reminder, Flint provides some key rules to aid in our discussion of structure and agency. I repeat them below (p. 43):
Agency is the actions behind trying to achieve a particular goal. Individuals or groups act, or have agency. Sometimes we can talk about states or a social movement having agency, but at other times it is more appropriate to think of groups or individuals at a lower scale (i.e., the President and the Pentagon acting differently to negotiate the defense budget). Agency is related to geopolitics in that it creates spaces (i.e., a nationalist group tries to create a nation-state) while actions are framed or situated within spaces.