A baby horse is known as a foal.
A foal is a young horse, typically less than one year old. Foals are born with a long, woolly coat and are usually able to stand and walk within a few hours of birth. Foals are typically weaned from their mothers at around six months of age, and are usually fully grown by the age of three. Foals are usually very playful and curious, and can often be seen running and playing in the fields.