in the last days - meaning, the days of the Messiah (Isa 2:2); as closing all preparatory arrangements, and constituting the final dispensation of God’s kingdom on earth.
pour out of my Spirit - in contrast with the mere drops of all preceding time.
upon all flesh - hitherto confined to the seed of Abraham.
sons ... daughters ... young men ... old men ... servants ... handmaidens - without distinction of sex, age, or rank.
see visions ... dream dreams - This is a mere accommodation to the ways in which the Spirit operated under the ancient economy, when the prediction was delivered; for in the New Testament, visions and dreams are rather the exception than the rule.