The premolars are the baby molars your colt starts out with. They are replaced, as he grows, by permanent molars – or adult molars.
Your colt has 3 premolars on each jaw line for a total of 12 teeth.
The wolf tooth is also a premolar. If your horse gets them they will be in front of the first 3 molars. The wolf tooth premolar doesn't get an adult tooth to replace it.