I believe this question is in terms of AP-Human Geography.
A surplus of food would advance hunter-gatherer societies because when a society begins, it's main concern is the gathering of food and resources for its people. If this was not a need, and the need was taken care of by a surplus the civilization would advance rapidly, focusing on advancement and development of the society itself.
This is because the concern and the amount of resources and people required and used to collect food would no longer be needed, and those resources and people would instead spend their time and lives, developing the society in other ways, therefore rapidly advancing the civilization.
