Sea. Exodus 15:20-21
Miriam is the sister of Moses and she is singing about the salvation of the Hebrew slaves and the destruction of the Egyptians at the Red Sea.
Miriam is actually continuing a song begun by Moses. He sings in Exodus 15:1-18 about the event and Miriam leads the women in singing the first verse of Moses as a refrain.
Her words have also been made into songs. They are used at the end of the Passover meal by Jews and also as a praise and worship song by Christians. You can also find the words in the second part of Handel's Oratorio, "Israel in Egypt."
