The equation of Verhulst-Pearl logistic growth is $\frac{dN}{dt}=rN\left[\frac{K-N}{K}\right]$. From this equation, $K$ indicates:

In the logistic growth equation, $N$ is population density at time $t$, $r$ is the intrinsic rate of natural increase, and $K$ is the carrying capacity (the maximum population size an environment can support).