Heterozygous:
A genotype consisting of two different alleles of a gene for a particular trait (Aa). Individuals who are heterozygous for a trait are referred to as heterozygotes.

Using Pastel as an example, in a normal ball python the genes should look like

nnpp

nn= normal
pp= the normal gene that would be in place of the pastel gene

A pastel would look like this

nnPp

nn= normal
Pp= Pastel

As you can see in these genes Pp that it is heterozygous. Making a visual pastel, but it is heterozygous.

A super pastel would look like this

nnPP

nn= normal
PP= super pastel

This makes a homozygous form.