What does Exodus 8:7 mean?
When Moses and Aaron showed a miraculous sign (Exodus 7:10), Pharaoh ignored it (Exodus 7:13). This was partly because his own sorcerers seemed to have duplicated the feat (Exodus 7:11–12). Pharaoh had already rejected the command to free Israel (Exodus 5:1–4). He recently shrugged off a devastating plague (Exodus 7:20–23). Now, he turns to his magicians once again. He is probably looking for another excuse to dismiss the miracles which the Lord is doing. His entire nation, including his own home (Exodus 8:3–4), is now inundated with swarming frogs (Exodus 8:1–2).Whether by supernatural means or tricks, Pharaoh's occultists convince him they can do the same as Moses and Aaron. This was enough to make Pharaoh reject earlier signs (Exodus 7:13, 22). They seem to summon frogs, but apparently cannot control them. They cannot make them go away, otherwise Pharoah would not be forced to approach Moses with a plea that the plague be lifted (Exodus 8:8).
The next plague, involving small insects, will leave the Egyptian magicians stumped. They fail to duplicate it (Exodus 8:18). In fact, the pagan sorcerers point to it as a sign of truly divine power (Exodus 8:19).