In Exodus 2:4, 7, Miriam signifies the truth of the church at that time and the religion near them. (Arcana Coelestia 6727, 6739)

In Exodus 15:20, this signifies the glorification of the Lord from the good of faith with reciprocity. (Arcana Coelestia 8337, 8340) When men represent truth, the women related to them represent good. Here Miriam represents external good, and so she is called the sister of Aaron, not the sister of Moses. (Arcana Coelestia 8337)

8340. 'And Miriam responded to them' means a reciprocation. This is clear from the meaning of 'responding', when the subject is the ascription of glory to the Lord by means of a song, as a reciprocation. Among the ancients it was also customary in sacred worship to sing in choirs, in order - that is to say - that there would be one or any number of persons who could respond to the others, which represented a reciprocation and response, like that of the Church from heaven, and of heaven from the Lord. Such is the meaning in Hosea,

I will respond and sing to Him. Hosea 14:8.

And in Moses,

Then Israel sang this song, Rise up, O spring! Respond over it. Numbers 21:17.