Predator satiation is a way for some animals to avoid getting eaten by predators. Just like how a person might avoid being robbed by leaving their wallet at home, some animals have developed a way of protecting themselves by overwhelming their predators.
Let's say you have a bunch of trees filled with delicious fruits. The predators, like birds or squirrels, will come and try to eat as much as they can. However, if there are so many fruits that the predators can’t possibly eat them all, then some fruits will be left over, and the predators will have eaten their fill. These remaining fruits can then produce more seeds and grow into new trees. This idea of having so much food that it can’t all be eaten is called predator satiation.
There are some animals that use predator satiation as a defense mechanism. For example, cicadas live underground for several years, then they all emerge at once. There are so many of them that predators like birds can't eat them all, and many cicadas are able to mate and lay eggs. Some types of plants also use predator satiation by producing so many seeds that, no matter how many are eaten by predators, there are still plenty left to grow into new plants.
So, predator satiation is just a fancy way of saying that some animals and plants have developed a clever way to avoid being eaten by overwhelming their predators with too much food.