"Goes" should imply some direction, so it rather cannot be a correct answer in such a short, vague sentence. But "on chodzi do szkoły" could be translated both as "he goes to school" and "he walks to school".
To quickly answer:
chodzić = the Simple versions (to go, to walk)
iść = the Continous versions (to be going, to be walking)
To be walking without a purpose and direction can also be "chodzić".