A rod is a bar or a stick, like the curtain rods in your windows or the steel rods inside the structure of a building that help make it sturdy.
A rod can be a staff, like a walking stick, or a metal bar used in construction projects. In tarot card decks, rods are are a suit that's also known as "wands" or "batons." You fish with a rod too, a long flexible pole. Most parents today disagree with the old-fashioned saying, "Spare the rod and spoil the child," which basically means "your kid will be spoiled if you don't hit them with a stick now and then."