Jesus uses this question to challenge the people to pay attention to their own sins before they pay attention to another person's sins. AT: "Do not look ... brothers eye while you ignore the log that is in your own eye." (See: [[rc://en/ta/man/translate/figs-rquestion]])
This is a metaphor for a person's most important faults. A log could not literally go into a person's eye. Jesus exaggerates to emphasize that a person should pay attention to his own more important faults before he deals with another person's less important faults. (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-hyperbole]])