People need feedback in three distinct areas, even though all three could be considered "about themselves."
We need feedback on our behavior. Behavior is what a person says or does.
One person I worked with had developed the habit of saying, "That really ticks me off …" for just about anything. The verbal tic distracted others from what he had to say. We showed him video a meeting where he was present where he used that phrase three times within about ten minutes. Once he saw what he was doing, we could work on eliminating the behavior.
Another manager I worked was raised to show respect for authority by looking down. That worked fine at home, but in the office and meetings it made her seem weak. Once she became aware of the problem, she could move toward fixing it.
We also need feedback on our performance. Performance is the measurable result of our work.
I worked with a consultant who worked long hours and turned in excellent work product, but obviously wasn't considered a real performer who might make partner. It turned out that the problem was twofold. First, he often overproduced in one area, but did only minimally acceptable work in others. Second, he was doing nothing in the area of bringing in clients for the firm.
Finally, we need feedback on our communication. We need to check and see if and how others understand our instructions and other communications.
Why do we need all of this? For two reasons.
Reason number one is that the most successful people are realistic about the present and themselves while remaining optimistic about the future they're working to shape. Feedback helps you maintain that important realism so that you can build on your strengths, make weaknesses irrelevant, and fix the problems that are fixable.
Reason number two is that it's human nature to have an unrealistic estimate of your own behavior and impact. Most people, for example, judge themselves by their intentions, while they judge others by their actions. For your life and career, though, most of the judging will be by others about your behavior and performance.