What does Exodus 8:14 mean?

In a sense, the second plague on Egypt (Exodus 8:5–6) did not end when God accepted Moses' request (Exodus 8:8–11). It only shifted into a form the Egyptians could resolve—but an incredibly disgusting one, all the same. The frogs teeming all over the land (Exodus 8:3–4) all die, suddenly. They don't fade away or dwindle until they are gone. The animals drop dead; Egyptians are forced to collect and pile up the carcasses. Depending on the location and time of year, the Nile Delta region can be humid, so these mounds would not necessarily dry up quickly. As this verse notes, there were so many rotting frogs that the stink was everywhere.

As predicted (Exodus 3:19–20), Pharaoh will use even the slightest relief as an excuse to go back on his word. As soon as the frogs are in piles, and not hopping into everyone's food, he drops his promise to release the Hebrew slaves (Exodus 8:15).