Complex sentence: In agriculture, a plowshare (or ploughshare) is the cutting or leading edge of a moldboard (or mouldboard) which closely follows the coulter (one or more ground-breaking spikes) when plowing (or ploughing).
Split into simpler sentences: In agriculture, a plowshare (or ploughshare) is a component of a plow (plough). It is the cutting or leading edge of a moldboard (mouldboard) which closely follows the coulter (one or more ground-breaking spikes) when plowing (ploughing).