Explain why generally only the male child suffers from colour blindness and not the female?

Generally the male child suffers from colour blindness because the genes responsible for most common inherited colour blindness are on the $X$ chromosomes (Sex-linked). males have only one $X$ chromosomes and females have two, this kind of inheritance pattern is called $X-linked$ and primary effected male.

In the females a functional gene on only one of the two $X$ chromosomes is sufficient to produce normal colour vision.