Even this early, babies can recognize faces and gestures intuitively — and sometimes even imitate them. Try putting your face close to hers and sticking out your tongue or raising your eyebrows a few times. Then give your baby some time to mimic your gesture.
Even if your baby doesn't copy your expression now, she's keeping close tabs — and learning. If you interact with her and she doesn't seem receptive at all, don't worry. She may have gotten sleepy or a bit overwhelmed and need to take a break.