What does this equation mean?

An accounting identity makes the consequence visible. Let $G_t$ be the number of claims placed before some audience in period t , let $A_t$ be that audience’s total attention budget, and let $c_v$ be the average attention cost of verifying one claim. The number of claims that can be verified, and the fraction $\phi_t$ of what arrives that is actually checked, are then $V_t \;=\; \frac{A_t}{c_v}, \qquad \phi_t \;=\; \frac{V_t}{G_t} \;=\; \frac{A_t}{c_v \, G_t}$. This is bookkeeping, not a finding. Its only content is what it forbids. Simon’s point was that $A_t$ is bounded by hours and by human processing capacity, and that this bound is not responsive to technology in the way that $G_t$ is. If $G_t$ rises by an order of magnitude, $\phi_t$ falls by an order of magnitude unless $c_v$ falls proportionally or $A_t$ expands proportionally. Institutions are the mechanism by which societies have historically pushed on $c_v$ . Nothing pushes usefully on $A_t$ .