Het is short for heterozygous. It means that the animal carries one (1) copy the recessive gene, but does not visually express it. It will never "look" pied, but when paired with another snake that also carries the pied gene, they can each pass down a copy of the pied gene (called an allele) and produce pied babies. When an animal has two (2) copies of the gene, it's known as homozygous. Recessive genes will be able to be seen (pied, albino, clown, ect) and co-dom genes will appear in their super form. A homozygous animal is guaranteed to always pass down 1 copy of that gene to its offspring because it carries both. A heterogeneous animal has a chance at passing down the single gene it carries, but it's not guaranteed.
For just-a-pet purposes, if you want a pied you will have to buy a pied. For breeding purposes, you can buy two het animals then cross your fingers and hope.
