The consequences for eating the fruit of the tree of knowledge of good and evil were (1) physical death (mortality: the capacity for the spirit to separate from the mortal body); and (2) spiritual death (separation from God’s presence).
Genesis 2:16–17
16 And the Lord God commanded the man, saying, Of every tree of the garden thou mayest freely eat:
17 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
President Joseph Fielding Smith said:
“What did Adam do? The very thing the Lord wanted him to do, and I hate to hear anybody call it a sin, for it wasn’t a sin. Did Adam sin when he partook of the forbidden fruit? I say to you, no, he did not! . . . The Lord said to Adam, here is the tree of the knowledge of good and evil. If you want to stay here then you cannot eat of that fruit. If you want to stay here then I forbid you to eat it. But you may act for yourself and you may eat of it if you want to. And if you eat it you will die.”
(“Fall-Atonement-Resurrection-Sacrament,” address at Salt Lake City Institute of Religion, Jan. 14, 1961, in Charge to Religious Educators, 2nd ed. [1981, 1982], 124.)