Toriel is a Anthropomorphism. Meaning she is Half human, Half animal, The half animal is a Goat. Which explains the Goat Horns, the Goat fur, and the Goat Tail, and a Goat Snout. Everything else is human, Human Breast, Human eyes, Human Feet, Human a hands..Etc....

Lastly she has 3 toes on each foot instead of the 5 and she has 3 fingers plus a thumb on each hand.