The Capitol heads a totalitarian government that controls its population primarily through the yearly ritual of the Hunger Games. Though the full details of the society are not revealed until later in the chapter, it's useful to understand them. After North America was destroyed through myriad disasters, Panem was founded by the Capitol. Seventy-five years earlier, the Capitol's control was contested by the districts, which rebelled. In what is now termed the "Dark Days," the twelve districts were defeated and a thirteenth district was obliterated as warning against further rebellion.
The Capitol has an even more devious structure to keep its citizens in line, though: the Hunger Games. Every year, each district must supply, through a lottery process, two "tributes" (both aged 12 to 18, one male, one female), who are forced to fight to the death in a large outdoor arena until one victor remains. The expectation is that the Hunger Games be treated as a spectacle, a great source of entertainment that all citizens are obliged to follow as audience. The Games illustrate how thoroughly Panem citizens are at the mercy of the Capitol, since it keeps them subdued by making them complicit in the atrocities as audience. Really, the only "benefit" to the games is entertainment for the spoiled and entitled people of the Capital. President Snow thinks they help enforce his dominance in the districts.