Here are some excerpts from Swedenborg's "Arcana Coelestia" that help explain the inner meaning of this chapter:

AC 2610. In the internal sense of this chapter the Lord‘s Divine Rational is first treated of, which is represented by "Isaac" (verses 1-8).

AC 2611. Next the merely human rational, which was then separated, and which is the "son of Hagar the Egyptian" (verses 9-12).

AC 2612. After this had been separated, the spiritual church is represented by the same, namely, by Hagar’s son, as well as by his mother; which church and its state are treated of in (verses 13 to 21).

AC 2613. Concerning the human rational things that were adjoined to the doctrine of faith, which in itself is Divine (verses 22-34).

AC 2614. This doctrine together with those things adjoined is "Beer-sheba" (verses 14, 31, 33).

2612. This separation having taken place, the spiritual Church is then represented by the same character, that is, by Hagar's son, and also by his mother. That Church and its state are the subject in verses 13-21.