Business Savvy is an Aspiration Trait. All aspirations give your sim an extra trait so that they can complete their aspiration easier. Mostly this aspiration trait will give your sim certain moods or desires when performing a task related to the aspiration Fortune. Sims that choose a fortune aspiration get the Business Savvy bonus trait which gives them higher-than-average salaries from careers.
The definition of savvy encloses:
shrewdness and practical knowledge, especially in politics or business.
"The financiers lacked the necessary political savvy."
know or understand.
"Bob Pancakes would savvy what to do about Eliza."
shrewd and knowledgeable in the realities of life."