The archangel is the head of the race of angels. From what we know in Scripture, there is only one named Michael. The archangel Michael has led (and will lead) the angels in battles fought against the demons. Since the term "archangel" is mentioned only twice in the Bible, we have limited knowledge of what the archangel does.
The word archangel is the translation of the Greek ἀρχάγγελος (transliterated: archaggelos). Ἀρχάγγελος comes from the Greek words ἄρχω (transliterated: archō, meaning "head or first") and ἄγγελος (transliterated: aggelos, meaning "angel or messenger").
When Moses died, God buried him in Mount Nebo. Sometime after that, the archangel Michael and the accuser Satan were arguing about the body. The archangel did not accuse Satan of anything but rather said that the Lord would rebuke him.