Small beans refer to a type of bean known as azuki beans. It will help if you've heard of this delicious popular bean, because there's not really anything effective we can do with the meaning mnemonic from this point on. Just know that small beans are azuki beans.
The reading doesn't make sense either. If you know that small beans are azuki beans, then you know that this is referring to a thing known as azuki (あずき). Other than that, there's not much else to do.
Azuki bean paste is made of azuki beans, but it’s pretty high in sugar.