What does the Bible mean by shod your feet with the preparation of the gospel of peace?

I believe you are referring to a verse in Ephesians 6:15 - "And your feet shod with the preparation of the gospel of peace". In his epistle to Ephesians chapter 6 verses 10 to 18, Paul describes a battle ready christian, but not for a physical battle, Ephesians 6:12 - "For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places." The warfare is a spiritual, so are the weapons of war. Your feet shod, means just that - put your shoes on and you keep them on, that is whenever the call comes - you are ready to go (doesn't mean physical shoes on your feet, but readiness of mind). Peter tells Christians in 1Peter 3:15 - "Be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear"

The "gospel of peace" means that God offers mankind peace, Colossians 1:20-21 "And, having made peace through the blood of his cross, by him to reconcile all things unto himself; by him, I say, whether they be things in earth, or things in heaven. And you, that were sometime alienated and enemies in your mind by wicked works, yet now hath he reconciled". So that whereas all of humanity, through their sinful nature are enemies of God, the good news or the gospel is that God has made peace at highest cost, and it's now offered free to all who would accept it.