U.S. Navy Carriers and the Rest of the World
Under a narrow definition of aircraft carriers—large ships with a full-length flight deck for fixed-wing aircraft—the claim broadly matches current counts: the U.S. Navy has about 11 such carriers, more than all other navies combined. China has three, India and the United Kingdom have two each, and several other countries have one. By this specific ship category, the U.S. has more than the combined total of the rest.
The count depends on the definition. If helicopter carriers and amphibious assault ships capable of operating short-takeoff/vertical-landing aircraft are included, counts rise for several countries; the United States also operates such ships. Fleet inventory also does not mean every ship is combat-ready or deployed at the same time.