It is so much better to listen to what people say and do. It means that the person thinks that it is easy to either predict or see by your facial or body expressions what you are thinking or what you will do next. Think of poker players and how they hide their reactions to their cards.
This doesn't mean you can take vitamins or apply topical vitamin C and then bake safely in the sun, but you can help keep your skin healthy and supple by making sure you get enough of this antioxidant vitamin [source: Bouchez].
Applying a vitamin C serum topically to the skin can essentially keep your skin from turning brown (preventing and fading brown spots due to its melanin suppressing properties), as well as making your skin look brighter, fresher with a youthful glow.