'Zarah' in Hebrew, means 'to rise.' It's related the sun and the first appearance of its light.

In Genesis 38:30, 'Zarah' or 'Zerah' signifies that way that a person is reborn, with good rising first, and giving light.

In Arcana Coelestia 4930, in describing this 'Zerah' meaning, it says, "Unless there were light from good inwardly in man, he would never be able to see truths so as to acknowledge and believe them." See also Genesis 46:12, and Arcana Coelestia 4812, 4928.

4928. 'And afterwards his brother came out' means good which in actual fact is prior. This is clear from the representation of Zerah, to whom 'brother' refers here, as good. For he was the one who opened the womb, and so who was the firstborn, and on whose hand was the twice-dyed thread - such good being meant by him, see 4925. The reason 'afterwards his brother came out' means that good in actual fact is prior is that while a person is being regenerated good is not seen because it conceals itself within the interior man and flows into truth solely through affection in whatever degrees that truth is joined to it. When therefore truth has been joined to good, which is effected once the person has been regenerated, good reveals itself; for at this point good motivates his actions and good is so to speak the standpoint from which he sees truths since he is more concerned with life than with doctrine.