"Honor your father and mother, that you may long endure on the land that the LORD your God is giving you". You must not only honor them while they are in this world but even after they have died and left this world - there lies the meaning of "the land".
This honor, to which one obligated, comes from what the Holy One has endowed you with, Torah or money, any form of endowment. For if you have been privileged with Torah, labor at it for its own heavenly sake, day in day out, forever renewing. And if you have gained wealth, use it to do good deeds, prevent downtrodden knees from buckling. This is the meaning of "the LORD God is giving you" – honor them with what the Holy One has given you.