# Undoubtedly ... so large

"It is obvious that you do not know, because you were not born when I created them, and you are not very old". Yahweh uses mocking irony to emphasize that Job does not understand light and darkness.

# for you were born then

"for you were already born when I created them". The word "then" refers to the time when light was created and separated from darkness.

# the number of your days is so large

"you have lived so many years"