# I truly know that this is so

"I know that what you say is true"

# this is so

Here the word "this" refers to what Bildad said.

# how can a person be in the right with God?

"how can anyone be innocent before God?"

# argue

"dispute"

# he cannot answer him once in a thousand times

"Once in a thousand times" is an idiom that means "at all." Possible meanings are 1) "he cannot give any answer to God" or 2) "God will not answer him at all" (See: [[rc://en/ta/man/translate/figs-idiom]])

# a thousand times

"1,000 times"