"Does your stomach hurt?"
Translation:¿Te duele el estómago?
Dolorse is a reflexive verb that works like gustar.
Literally translated, it means "does your stomach hurt you"/"does it hurt you, your stomach?"
The conjugation of the verb depends on the thing giving/causing the pain. "Te duelen los dientes?" --> "do your teeth hurt?"
The "te" is what is used to indicate you are using the 2nd person informal.
"Nos duelen las manos?" --> do our hands hurt?
"Me duele la pierna" --> my knee hurts (it hurts me my knee)