Possible meanings are 1) "By the time that child is old enough to eat curds and honey, he will be able to reject what is evil and choose what is good." This emphasizes that the child will be very young when he knows to choose what is right instead of wrong or 2) "By the time the child is old enough to reject what is evil and choose what is good, he will be eating curds and honey." The people of Judah considered a child to be responsible for doing what is right when he was 12 years old. This emphasizes that within twelve years the people will be able to eat much curds and honey because most of the people of Israel will be killed or taken as captives. (See: [[rc://en/ta/man/jit/figs-explicit]])
Here "the evil" and "the good" refer to evil and good things in general. Alternate translation: "refuse to do evil deeds and choose to do good deeds" (See: [[rc://en/ta/man/jit/figs-nominaladj]])