It means that the horse has the correct qualities needed to be a harness horse.
did you mean harness?
To remove a harness from (a horse or other animal).
does a horse pull a cart with the harness, or does a horse push the cart with harness from the front
"trace chains (n): the chains that connect a horse's harness to a vehicle."
For horse isle it's Trace. In general too.
Search 'horse harness parts diagram. You will find a few sites.
The horse's harness was made out of leather.
on their head it's called a halter but when they pull a cart its just a harness.
The basic harness item your horse should have is a breastplate or standing martingale
a harness and a saddle
I put the harness on the horse.
the basic harness for moving your horse around the field is usually a halter.