This quote is suggesting that appearances can be deceiving. This means that the things that we show to the world, such as our behaviour and accomplishments, may not be an accurate representation of who we really are. This can be true in any situation, from the way we present ourselves on social media to our relationships with others. We might act a certain way around one group of people, but be very different around another. Our true selves are usually hidden behind a facade or mask that we put up to protect ourselves and project a certain image. This quote is reminding us to be careful about judging someone, because the reality may be very different from what we expect.