Would someone give me the meaning of the red highlighted sentences?
I have no idea about the relationship between apples, oranges, lemon, and bananas, especially "lemon" and "bananas".
Similarly, if their comination involves arbitrary decisions, the results provide potentially misleading results. (As an aside and in a somewhat lighter vein, it is well known that, if you add apples and oranges, the answer is a lemon; but if you subtract apples from oranges, the answer can be totally bananas.)
Pope of the Dictionary.com Forum