When the Torah sums up who stood before Pharaoh to demand Israel's release, it simply says these are they (Exodus 6:27). Targum Pseudo-Jonathan on Exodus 6:27 supplies the titles: it is Mosheh the prophet, and Aharon the priest.
Two offices, two brothers, one delegation. The meturgeman is not just labeling them; he is teaching the architecture of redemption. Israel is freed by the pairing of prophet and priest — the voice that receives God's word and the hands that draw near to God's service. Neither alone would have been enough.
Moses without Aharon would have been a solitary blaze, a burning bush with no one to carry the fire to the altar. Aharon without Moses would have been a beautiful voice with no message to carry. Together, they became the template for every later generation of Jewish leadership: the Torah sage and the serving priest, the word and the deed, the lonely prophet and the community's minister.
The takeaway is practical. The Jewish people have never been led well by one office alone. Prophecy without priesthood becomes unmoored; priesthood without prophecy becomes routine. Pharaoh saw both men at his palace door, and that is the only combination that has ever loosened a tyrant's grip.