fighting against Keilah

"Keilah" is the name of a town. Here "Keilah" represents the people who live there. Alternate translation: "fighting against the people of Keilah" (See: rc://en/ta/man/translate/translate-names and rc://en/ta/man/translate/figs-metonymy)

threshing

separating the grain or seeds, generally from a cereal plant or wheat by some mechanical means