What Albright means here is that the United States is the most important country in the world in terms of keeping the peace and order of the world intact.
Albright spoke these words in the context of the issue of Iraq and the weapons of mass destruction program that it was believed to have in the late 1990s. She said that the US was indispensable for keeping countries like Iraq from doing things that would upset world peace. She said, basically, that the US was more forward-looking and better at understanding the long-term consequences of today's events than any other country.
Between this quality of the US and its military power, it was the most important country in the world.