The answer is its height, which is measured in 'hands'. Hand height We still measure the height of horses and ponies the way that we always did - in hands. You measure from the ground up to the withers. By fourteen you will probably be riding a horse. The important thing is that the animal is the right size for you, and you for it.
Different horses do different jobs.
Heavy workhorses are used for pulling things - a farm plough, for example. Racehorses, which are descendants of Arab stallions, can sprint at over 65 km per hour. When you greet your horse or pony make sure it can see you. Don't shout or wave, because a startled animal may kick out or gallop off. Chunks of apple and carrot make great treats for your pony, but watch how you offer them.