My 12 yeat old child have mole on his right ear?

Moles. These are generally not serious at this age, but should be checked by your pediatrician, when seen. This is also a reminder about how important sunscreen is for prevention.
See doctor. Without being able to see the mole, it's impossible to tell you if it's ok or not. His doctor can look at it and tell you if you need to have him see the dermatologist.