Question: "What does Jonah 4:11 mean by people who cannot tell their right hand from their left?"
Answer: In Jonah 4:11 God speaks of “more than 120,000 persons who do not know their right hand from their left.” Who are these 120,000 people?
First, it is obvious from the context that these people were residents of Nineveh. Jonah was angry at God’s compassion toward the Ninevites who repented after hearing Jonah’s preaching. Chapter 4 specifically focuses on God’s love toward those in Nineveh and His mercy in response to their repentance.
However, the precise identity of these 120,000 Ninevites is problematic. The clause “who do not know their right hand from their left” is not found in any other biblical passage or comparative Hebrew literature. The expression is interpreted to mean either young children who have yet to learn right from left or adults who do not understand right from wrong.
Those who conclude the 120,000 are young children appeal to a straightforward reading of the words used in modern translations. The idea of not knowing “right” from “left” naturally evokes thoughts of young children—usually five years old and younger—who do not understand this difference. However, if Nineveh contained 120,000 young children, the population of the city must have been at least 600,000. The problem with this is that the area within the city walls would not have contained more than 175,000 people, according to figures based on archaeological remains. (See http://www.studylight.org/dic/hbd/view.cgi?number=T4620.)
Those who conclude the 120,000 people comprise all of the Ninevites provide an array of convincing evidence. First, the Hebrew word translated “people” in Jonah 4:11 is the general word for “people,” not the Hebrew word for “children.” Linguistically, the evidence favors a broader interpretation that includes all the people of Nineveh.
In addition, the closest biblical parallels refer to the difference between those who know the Law of the Lord and those who do not. For example, Ecclesiastes 10:2 says, “A wise man's heart inclines him to the right, but a fool's heart to the left.” The Bible often speaks of the wicked as those do not know God (Proverbs 28:5; Galatians 4:8; 1 Thessalonians 4:5; 1 John 4:8). On the cross Jesus prayed for the Father to forgive His murderers, “for they do not know what they are doing” (Luke 23:34; see also Acts 17:23, 30 and 1 Timothy 1:13). In Hosea 4:6 we read, “My people are destroyed from lack of knowledge.”
Further, a parallel is made in Jonah 4:11 between the people and the livestock of Nineveh. It is much more likely the parallel refers to all people/all livestock versus only young children and livestock.
Finally, it makes sense for the 120,000 to include all Ninevites because God showed compassion on the entire city, not just on its young children and animals.
Jonah 4:11 most likely refers to those who, spiritually speaking, cannot tell right from left. The verse shows that God takes pity on the spiritual blindness of the pagan. God’s desire is to extend His salvation to all who repent and turn to Him.