What are flops and how are they benchmarked?
As far as I know, they give peak performance values. Given clock speed $f$ (in Hz) and number of cycles per (shortest) floating point operation $c$, the peak performance is essentially $f \cdot c$.

Of course, modern machines execute multiple floating point operations in parallel, have multiple cores etc. A more accurate formula can be found on Wikipedia.

This measure ignores all of the pain any real program encounters, e.g. cache misses and pipeline stalls. That is, any (reasonable) benchmark will not reach this number. But as an (unattainable) ultimate figure it can be useful to compare machines and even programs (how close to peak performance do they get?) -- take such statements with a grain of salt, always.