BVH Hip Location Limits
The values for hip location can range from -196.8504 to 196.8504 along each axis. Each axis is 10 meters long. This means you can move an avatar from its origin up to 5 meters in any direction.
The reason for the strange input to output relationship is Linden Lab decided to use inches as a measure of distance in animations, while everything else in Second Life is metric. Since 1 inch = 0.0254 meters, 5 meters/0.0254 meters per inch = 196.8504 inches from origin.
Be aware that you normally want to use a sit target, instead of hip location, to precisely place avatars. Sit targets can be adjusted without paying another upload fee, unlike hip locations in animations.
Animating hip location is useful when you need to depict the avatar moving, when it is, in reality, sitting still. A practical example would be a Electric Slide animation for a dance poseball, where you would use it for the side-to-side motion.
You will probably have to experiment with your BVH exporter to get it to match the in-world behavior, since it most likely does not use inches.