en_tn/1sa/14/13.md

The Philistines were put to death before Jonathan

AT: "Jonathan killed the Philistines" (See: rc://en/ta/man/translate/figs-activepassive)

his armor bearer put some to death behind him

Jonathan's armor bearer followed behind Jonathan and also killed Philistine soldiers.

killed about twenty men in about half a furrow’s length in an acre of land

This phrase shows that Jonathan killed the men quickly one directly following the next.

furrow's

A "furrow" is about one half of an acre.