'Spill' has been used as a verb with the meaning of 'divulge' or 'let out' since at least the 16th century. But how do beans come to be a part of this phrase. Read about the ideas on the origin here . If the theory surrounding the one for the early 20th century is accurate then the meaning hasn't changed. It means to divulge a secret and usually to do so knowingly and/or with malicious intentions.