In the poem "After apple picking" Robert Frost uses many metaphors to create this story
I believe the apples stands for certain goals that he can and can't reach. The more difficult goals would be at the top and the easiers ones that he can reach are towards the bottom.
In the beggining he talks about a ladder and I think that has to do with the reasons he can't reach certain goals aka the apples. I'm not sure whether the ladder stands for money or other limitations.
One of the literal meanings of the poem is about the narrator picking apples during harvest season.
Another one of the literal meanings in the poems is the narrator getting tired from apple picking and going to sleep.
In this poem he is picking apples that repersents him reaching for his goals in life. Since he keeps picking apples he is not reaching his goals. Eventally it will just be a routine and he will die without reaching his goals.