huparchō

This is a quiet, dignified way of saying that something is the case. Greek had a plain everyday word for "to be" (the verb behind "is" and "was"), and this word is a more formal cousin of it. When a writer chooses it, he is usually pointing not just to bare existence but to a person's or thing's standing condition: what someone already is, by birth, status, or nature, before the action of the sentence even begins.

The word leans on that settled quality. Paul says he was advancing in Judaism while "being" a zealous Jew, the angel-like onlookers in fine clothes "are" people who live in palaces, and most famously Christ, "being" in the form of God, did not grasp at equality with God. In each case the word frames a fixed starting condition that the rest of the sentence builds on.

A close shade of the same idea is existence understood as availability or belonging: a thing "is there" for someone, at hand or at their disposal. Peter tells the lame man that silver and gold "are not" his to give, and Luke notes that estates "belonged to" the chief man of the island. Here the line between simply existing and being someone's property is thin, which is exactly why the same word, used as a noun in the next meaning, comes to mean the possessions a person has.

When the verb is turned into a noun, in the plural form "the things one has," it names a person's material possessions: goods, property, an estate, whatever they own. English Bibles render it goods, possessions, property, or substance.

This is where the word does some of its sharpest work in the Gospels. Jesus tells the rich young ruler to sell everything he has, warns that life does not consist in the abundance of one's possessions, and says no one can be his disciple who does not give up all that he has. The same noun describes the early believers in Jerusalem, who held nothing they owned as their own. The shift from "to be" to "the things that are mine" is small in Greek but pointed: what a person owns becomes almost an extension of who they are, which is exactly the assumption Jesus challenges.