The speaker believes that eyes are honest and lips are not. Eyes, they say, show every emotion as clearly as a high-definition TV screen, so anyone who really looks can read the truth. Lips, on the other hand, are "the holder of all lies," a "thing stuck on your face" that hurts other people and the person using it. Even a smile, the poem suggests, can be part of the cover-up.
The tone is confident, almost defiant. "I'm not stupid" sounds like someone who has been fed false words before and learned to look past them. The repeated "lips lie" has a blunt, chant-like feel, as if the speaker is convincing us as much as themselves. The ending shifts to something warmer. Speaking directly to "you," the speaker promises they will see through a smile and a casual "I'm fine" to the pain underneath. That final turn makes the poem feel less like an accusation and more like a quiet offer of care.