Answer:
Probability may be defined as the chance of happening of any event. The probability concept is used in the genetics as well to understand the inheritance probability of the parents and offspring.
M stands for the male selection and B represents the selection of the blue eyes. The (M|B ) represents the probability of the getting male with the blue eyes. The (M|B ) and (B|M ) are different because (B|M) shows the probability of the individual with blue eyes and the male has been selected.