“will be satisfied with bread.” Proverbs 12:11 is one of the many “ideal” promises in the Word of God which would be fulfilled here on earth today if we lived in a godly world with godly people. We do not. The Devil is the god of this age (2 Cor. 4:4; 1 John 5:19), and between bad weather, bad politics, wars, and evil people, a person who works his land sometimes goes hungry anyway. This promise will only be fully fulfilled in the future.
[For more on promises like this, see commentary on Prov. 19:5.]
“sense.” The Hebrew word is leb (#03820 לֵב), which is often translated “heart,” but this is one of those cases where that translation would cause confusion. In modern English, the word “heart” usually refers to emotion or passion, but that is not its meaning here. The function of the brain was unknown in biblical times, so things that we generally assign to the brain, like thinking, attitudes, understanding, and good sense, were assigned to the heart. In this case, a fool who pursues worthless things lacks “sense.”
[For more on the Hebrew word leb and “heart,” see commentary on Prov. 15:21, “sense.”]