Here the word "eye" is a metonym for either 1) desiring to sin by looking at something. AT: "If you want to do something sinful by looking at something, tear your eye out" or 2) Desiring to sin because of what you have looked at. AT: "If you want to do something sinful because of what you look at, tear your eye out" (See: [[rc://en/ta/man/translate/figs-metonymy]])
This refers to the state of a person's physical body when he dies. A person does not take his physical body with him into eternity. AT: "to enter into the kingdom of God after having lived on earth with only one eye than to have lived on earth with two eyes" (See: [[rc://en/ta/man/translate/figs-explicit]])