A negligible amount. This phrase is most often heard as “that doesn't amount to a hill of beans.” The underlying idea is that beans are so common that even a hill of them isn't worth very much, if anything at all. The Yiddish word for “beans” is “bupkes,” which has been adopted into American English to mean “absolutely nothing.” You'll hear it at card games and racetracks when a disgusted player tosses in his hand or tears up a losing pari-mutuel ticket with an exasperated “I got bupkes.”