In 1 Nephi chapter 8 verse 10 it talks about a “tree, whose fruit was desirable to make one happy”. What is the symbolism of the fruit?
If you look at the footnote to the word, fruit, in verse 10, it will lead you to Alma 32:42, which describes the qualities of the fruit. The definition of what the fruit is, is given in the preface to Alma 32, that states—
Then it grows into a tree from which the fruit of eternal life is picked.
So it appears that the fruit of the tree of life that father Lehi saw in vision is eternal life.