My 8wo had pead check up, he said she not to visit my friend who has internal staph infection from surgery. She says she not contagious, plse explain?

Extra cautious? I think the pediatrician is just being extra cautious. Even with "internal" infection, your friend could have staph on skin or in the environment in her home. OTOH, we're all exposed to staph. Other friends, you, and your family could have it at any time, and sooner or later your baby will be exposed to it. The doc may just want to avoid particularly heavy exposure until more mature immune system.