My son is now 16 months old. My older son is 3. Totally typical. He has no real idea of what's going on, except he thinks is hilarious that you sometimes do this "new" face with this "no" word. It's hilarious to him. He's just now learning about what is appropriate and when. A lot of babies this age also like saying "no" a lot themselves because they hear it so much. When my baby hits me (usually I hold him). I say "gentle" and show him how to touch gently. Or if he continues to hit. I say "no hitting" and I put him down. He loves me to carry him around so putting him down is an immediate consequence to hitting. He picked up on it pretty quickly. Hope this helps!