so, thus: pointing back to a manner, situation, or statement just named
This is one of the most common little words in the Hebrew Bible, and almost all of its work is pointing. It looks back at something just said or done and says, in effect, like that. When God speaks and the narrator adds "and it was so," the word is doing nothing more than confirming that the result matched the command. When someone is told to act and the text says they "did so," it means they did it in exactly the way described.
From that core of pointing back, the word reaches into a few settled jobs. In a comparison it supplies the second half: just as one thing is true, so the other is true. Welded to a small preposition it becomes the everyday word for "therefore" or "that is why," the hinge a writer uses to draw a conclusion or to explain how a place got its name. Joined to a word for "after," it simply means "afterward."
What holds all of these together is that the word never names a thing on its own. It always borrows its content from the manner, situation, or statement it refers to, and then hands that content forward to the next clause.