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

AC 4811. The subject treated of in this chapter, in the internal Sense, is the Jewish Church and the genuine church; the Jewish Church is described by Judah, and the genuine church by Tamar.

AC 4812. The sons by Tamar signify the two essentials of the church, namely, faith and love--Perez faith, and Zerah love. Their birth represents that love is actually the firstborn of the church, and faith only apparently so.

4812. His sons by Tamar mean the two essentials of the Church, which are faith and love - Perez meaning faith and Zerah love. Their birth represents the truth that love is in actual fact the firstborn of the Church, and that faith only appears to be this.