This is an interesting question. When I started meditating, I wasn’t expecting it to teach me anything about myself. Like most people, I thought meditation was about “switching off” my brain, “clearing my head” or just relaxing. And to be fair, it may have done that to some extent, but that’s not been the big "win" of meditation for me. What meditation actually does is encourage you to look within. It helps you get to know yourself. So, what does meditation tell me?
One thing that I learned through meditation is just how noisy my mind is. When I sit down to meditate, I am plagued with thoughts - sometimes annoying, sometimes entertaining, often very random thoughts. And I realize how much of my time I spend being lost in those thoughts. So much of my life I don’t even notice the fact that I am caught up in the narrative of my chattering mind. But when I meditate, I tune into it and I notice it all. (Read more on this in Your Mind Isn't Actually You: How to Quiet the 'Monkey Chatter.')
I also notice that the appearance of my thoughts is not within my conscious control. When thoughts pop into my head, they happen just like that. Most of the time, I don’t invite them in or seek them out, they just pop in, unannounced and unexpected. So, through meditation, I discovered that those thoughts are not really me, or at least they’re not an aspect of me that’s within my conscious control. And in doing so I realized how little they matter.
What I did learn about myself is that although I might not be able to control the appearance of my thoughts, I can moderate how I respond to them. Where previously I’d get tangled up in internal dialogue with even the most insignificant, unnecessary and sometimes actively self-destructive thoughts, through meditation I saw them for what they really were - just thoughts. I did not have to engage with them and they lost a lot of their power over me.
And this leads to the most revelatory thing that meditation taught me about myself. By learning to take a step back from my thoughts and to observe them rather than automatically engage with them, I realized that a deeper aspect of my consciousness existed. I learned that there is a part of me which sees all that happens to me, including all my thoughts and feelings, but is fundamentally untouched by them. There’s a part of me that’s always okay anyway. Regardless of what happens, it’s reassuringly constant and unchanging.
And so meditation can teach you not only what your mind is like, but also what you are in the deeper sense of your consciousness, and what it means to be human. It helps you not only to theorize, but to actively explore and experience the question of, "Who am I?" (Read more in How can I hear my inner voice?).