Answer: it is an extended metaphor that compares the mother's life to a staircase.
Step-by-step explanation:
In "Mother to Son" Hughes uses a metaphor to describe the life of the mother. In this case, it is an extended metaphor that compares the mother's life to a staircase. Each step symbolizes a part of her life that she had to endure. This metaphor is used throughout the poem to show the meaning of the poem.