can anybody explain these lines ?

"inhibiting sexual maturation" is just that... stopping the progress of the female's reproductive growth... they don't develop normally because if they did, they'd be getting pregnant and there'd be over-population, so they stop it from continuing or developing. It's a natural phenomenon that's quite common in the animal kingdom.

And the three generational thing is that this could last for three generations. Not their lifetime, I believe, but litters.