Answer:
Women have 2 X chromosomes, unlike men who have XY. In women, a recessive allele on one X chromosome is often masked in their phenotype by a dominant normal allele on the other.
Step-by-step explanation:
In informal words, if you have an X-linked trait that is recessive and are male, you will be affected cuz there is no other X to "override" that recessive trait because Y is (as we know) non-coding. Whereas if you are female, both of your Xs would have to carry a recessive trait for you to be affected, thus it is rarer for women to be affected by X-linked traits.