What does directive force magnets in a compass mean mesn?

It is the component of the earths magnet field which aligns the compass needle to the Magnetic North Pole.

The Horizontal Component (directive force) is the greatest at the magnetic Equator (Aclinic Line), where the vertical component is the weakest.

Above the magnetic north pole, it is the opposite. The Horizontal, or directive force is weakest and the vertical component is the strongest.