· What do all these 1.2.3 numbers mean before animal species that people post?
The numbers are in the format M.F.U.
M == Males
F == Females
U == Unknown.
So, if somebody posted saying they had 2.4.10 Bearded Dragons, that would mean they have 2 males, 4 females, and 10 that are otherwise unknown (probably meaning they're too young to be sexed in this case).
"Het" is an abbreviation for heterozygous. This means that an animal is carrying a recessive genetic trait, however is not actively displaying the characteristic - it has only inherited the trait from one of its parents.
This is as opposed to homozygous - inheriting the trait from both parents and displaying it.
For example, an animal that is homozygous albino, will look albino. If you breed this albino to a normal looking specimen of the same species, all the babies will be said to be "het" for albino. They will inherit the gene from one parent, but not from the other.
As recessive genes are required to be in pairs (one from each parent) in order to be displayed, het animals, as a general rule, show no obvious signs of carrying the trait.