Happy is he that hath the God of Jacob for his help - Who may rely for protection on the God who defended Jacob in his travels and dangers. Or, perhaps the word Jacob is used here collectively to denote Israel - the Jewish people: the God whom they adore and worship, rather than the gods of the pagan. Compare Psalms 144:15, note; Psalms 54:4, note.
Whose hope is in the Lord his God - In Yahweh, worshipped as his God. That is, who truly worships Yahweh, or makes Yahweh his God.