The Torah calls Miriam “the prophetess” at the splitting of the sea and the Talmud enumerates her as one of the seven prophetesses:
Miriam prophesied that her mother would give birth to a son who would redeem Israel. When Moshe was born and the house was filled with light, her father got up, kissed her and said, “My daughter, your prophecy has been fulfilled.” When they put him in the Nile, her father rose, struck her head and asked, “My daughter, what will become of your prophecy?” Therefore, it states, “His sister stood from afar” (Shemot 2:4) to find out what would be the end of her prophecy (Megillah 14a).
According to the Talmud, it is not clear why Miriam was called a prophetess at the sea rather than prior to the birth of Moshe, when she originally prophesied. Etz Yosef explains that only at the culmination of the Exodus did Miriam’s prophecy become totally fulfilled. Rabbeinu Bachaya notes that Miriam is the first person to be named a prophet in the Torah. The first time the Torah mentions the word “prophet” is in regards to a woman, in order to emphasize the great level that women attained at the sea, as it states: “A maidservant at the sea saw more than even Yechezkel ben Buzi” (Mechilta, Beshalach 3). Kli Yakar agrees that Miriam became a prophetess at the splitting of the sea, since the women merited seeing the Shechinah at that time. They played drums and danced in order to draw down the spirit of prophecy, as the Divine Presence only rests upon us when we are filled with happiness (Shabbat 30b).
Rabbeinu Bachaya concludes that important matters in the Torah are often expressed through women. For example, the concept of the World to Come is called “a bundle of life” by Avigail, wife of David (1 Shemuel 25:29). Channah, the Mother of our Prayer, taught the concept of the revival of the dead (1 Shemuel 2:6), and the order of prayer. Reincarnation is alluded to by the wise woman from Tekoah (2 Shemuel 14:14). All these instances show the importance of the role of women in the Torah.