Although Moshe Rabeinu is mute, Hashem tells him not to worry but to go with his brother Aron and both should address Paroah. First Moshe should repeat Hashem’s words exactly in Lashon Hakodesh (although Paroah wouldn’t understand) and then Aron should translate it, explain it and try to convince Paroah to let the Jews go . The question arises: if that is indeed the case, what is the point of Moshe just repeating Hashem’s words if Paroah would not understand them?The answer is that Moshe was a messenger from Hashem. The fact that he was mute meant that he was completely nullified to Hashem, and therefore, had no words of his own. It was actually Hashem’s voice coming out of his mouth. Since only Hashem has the power to break evil when evil is at its peak, therefore, only a Moshe Rabeinu who was completely one with Hashem, was able to break this power. The lesson we derive is that being connected to the Moshe Rabeinu of our generation gives us the power to overcome all challenges.

לקו״ש טז-ג