The poem is a riddle. The speaker never says the word "money" until you work it out from the clues: it pays for food, drinks, rent, a car, and a family's education and shelter. The final lines give the answer away by naming the speaker "a piece of paper."
What makes it work is the speaker's voice. Money talks like a proud, slightly menacing ruler, claiming that the world "revolves around me, like the earth to the sun." It brings "tremendous joy" and "great stress," and it can both wreck a life and carry someone through another day. The speaker seems cold and certain of its hold, and it admits it has "no pulse or heartbeat." That detail is unsettling: something lifeless runs human lives.
The mood is heavy and uneasy. The repeated "unable" and "able" lines pile up like a list of demands, and the image of "heavy darkness" overhead when you run short captures the constant worry that comes with needing money.