Nephi says in 1 Nephi 5:14:
And it came to pass that my father, Lehi, also found upon the plates of brass a genealogy of his fathers; wherefore he knew that he was a descendant of Joseph; yea, even that Joseph who was the son of Jacob, who was sold into Egypt, and who was preserved by the hand of the Lord, that he might preserve his father, Jacob, and all his household from perishing with famine. (emphasis added)
Matthew L. Bowen comments on this scripture:
Indeed, there appears to be an allusion to the meaning of Jacob’s name (“may he protect”) in the verb translated “preserve” (cf. Genesis 32:20: “And Jacob called the name of the place Peniel: for I have seen God face to face, and my life [soul] is preserved [wattināṣēl napšî]”; Genesis 45:5: “God did send me [Joseph] before you to preserve life [lĕmiḥyâ]”). It is worth noting here that the Semitic verb ʿqb as preserved in the Ethiopic verb ʿaqaba (“guard, watch, keep watch, safeguard, tend [flocks], preserve … protect”) and substantive participle ʿaqābbi (“guardian, guard, keeper, watchman, protector, official” cf. kjv Akkub) and South Arabic ʿqbt(n) (“watchtower”) and *mʿqbt (“guard, guardian”) convey this sense of protection.– Matthew L. Bowen – Jacob’s Protector
Where would Joseph Smith have found out the meaning of the name “Jacob”?