Why Are There Males & Females In This World ?

The very nature of how Allah SWT creates, and sustains is full of wisdom. It is not possible for us to comprehend all the wisdoms in the creation of Allah.

However, in our limited understanding, some wisdoms are:

a) To comfort one another,
b) Procreation
c) The father to guide and nurture the children; and
d) The mother to show affection to the children.

And Allah Ta'ala Knows Best