It means,
For men : you got to button All the buttons on the side of your overalls, your Tshirt should have a pocket, wear your Sunday boots, and no ball caps (cowboy hats and stetsons are ok).
For Ladies: Shorts no more than 12 inches above the knee and no writing on the back. Tank tops/tube tops must be yours not your 12yr daughter's, shoes or flip flops must be worn (at least until you get there).