She called his name Joseph - יוסף Yoseph, adding, or he who adds; thereby prophetically declaring that God would add unto her another son, which was accomplished in the birth of Benjamin, Genesis 35:18.

And she called his name Joseph,.... Which signifies "adding", or rather, "to be added"; or, "God shall add", giving this reason for it:
and said, the Lord shall add to me another son: which is expressive of strong faith; that as she had begun to bear children, she should bear another, as she did; though some read the words as a wish or prayer, "may the Lord", or, "and that the Lord would add", &c. (h); but our version seems best: the name Joseph is composed of two words, one which signifies to gather or take away, used in Genesis 30:23, and another which signifies to add; and so has respect to the Lord's taking away her reproach, and adding to her another son: Melo, an Heathen writer, makes mention of Joseph by name, as Polyhistor (i) relates, and makes him the twelfth and last son of Abraham, whereas he was the eleventh of Jacob. He was born, as the Jews say (k), the twenty seventh of Tammuz or June, and lived one hundred and ten years.
(h) "addat", V. L. Pagninus, Montanus, Junius & Tremellius, Piscator. (i) Apud. Euseb. Praepar. Evangel. l. 9. c. 19. p. 421. (k) Shalshal. ibid.