'Threshing' in the Bible

Now Ornan was threshing wheat, and Ornan turned and saw the angel, and his four sons with him hid themselves.

And Ornan said to David, "Take [it] to yourself; let my lord the king do what [is] good in his eyes. See, I give the cattle for the burnt offerings and threshing sledges for the wood and wheat for the grain offering--I give [it] all."