You can attack from horseback, either using your sword, or by trampling enemies in your way. You also have access to medium range rifles you can use to take out enemies from afar. Another thing you can throw from horseback are anti-vehicle grenades.
You can drop ammo and med packs from the horse’s saddlebags, similar to how light tanks dispense ammo and bandages. Although horses are mainly designed for quick attacks, their health pool is not small, but they do make you a bigger target.
You can spawn on one from the deployment screen or jump on any one you see unattended on the battlefield. DICE says a lot of time has been spent making them feel more like animals and less like motorcycles.
For instance, when you approach the edge of a cliff on a horse, it will refuse to go over. This is just an example of how horses will be able to recognise their environments, going throw shallow water and not swimming, for instance. They will also try to avoid or jump over obstacles.
Similar to the vehicle class, choosing to spawn on a horse will give you access to the cavalry class. Just like the recently revealed Elite Classes, horses will feature in the upcoming open beta for everyone to try out.