What does Genesis 15:5 mean?
The word of the Lord came to Abram in a vision, reassuring Abram of God's protection and reward. Abram responded with heartfelt concerns, pointing out that the Promise-maker still had not given to him any children. God assured Abram once more that his heir would be his own flesh and blood, not a servant. The Hebrew phrasing used in the prior verse explicitly referred to a biological child—a literal, natural "son" for Abram.Now God somehow shows Abram the stars. Given that this encounter is described as a vision, it's hard to know if this look at the stars was an illusion, or an actual trip outside. Later verses suggest that this part of the story happens prior to sunset (Genesis 15:12). In any case, God directs Abram to look up and count the stars above, if he was able. Of course, Abram could not count the stars. Neither could he count the dust on the earth, which God had pointed to in making a similar promise in Genesis 13:16.
God assures Abram once more that his offspring would be so numerous as to be uncountable.