A "rod" is actually a unit of land measurement. A rod is 16.5 feet. It's an old school surveyor's tool. I've heard that the measurement dates back to the Roman empire, where the soldiers were also road builders. In the version I was told, 16.5 feet was about the length of a Roman pike.

"Rods" were often a fractional unit of a "chain." A surveyor's chain is another old school tool. Chains were 66 feet in length. A chain is the same length as 4 rods. Back in the day when surveyors had more basic tools, a surveyor would start at a landmark, like a fence post, or a tree, or a metal marker. Then the surveyor would measure their compass heading and stretch out their 66 foot chain and take their measurements. When the distance got too small for the chain they would switch to the rod. A legal description written using this method would read something like "Commence at a fence post on the Southwest corner of the old Grantham tract, in the Southeast quarter of Section 32, Township 3 North, Range 4 East, thence run North 44 degrees, 35 minutes West 14 chains, 3 3/4 rods to the centerline of Redd Creek, thence run in a Northerly direction along the centerline of said creek..."