“Life for me ain’t been no crystal stair.
It’s had tacks in it,
And boards torn up,
And places with no carpet on the floor —
A mother compares her life to a crystal stair. She in fact compares her life to climbing up wooden, old and broken stairs that means how she faced difficulties and barriers in finding success in life.
Also, there is a lot of imagery with description, and we being readers can see what speaker is describing such as descriptions of splinters, tacks and image of crystal stair, which are specific images that allow us to visualize difficulties of life.