What does this equation mean?

One honest caveat belongs here rather than in a footnote. The estimate $t_*$ $\sim$ ($\beta$/2$\pi$)$\ln$ S treats emission as though every mode escaped with equal ease, when a real Schwarzschild hole’s greybody factors suppress low-angular-momentum, long-wavelength quanta relative to a naive blackbody count. That suppression changes the effective rate at which new, usable radiation becomes available by an order-one-to-few numerical factor; it does not change the logarithmic scaling in S that makes $t_*$ so much shorter than the hole’s own light-crossing or evaporation timescales, and it is exactly the kind of correction the fast-scrambling conjecture was framed to survive [ 2 ] . The millisecond figure below should be read as good to that order-of-magnitude, not to the third significant figure the arithmetic displays.