I am told i have a neeva mole and that it will turn cancer so surgery is scheduled will it always turn cancer?

Small number: nevi are part of the spectrum of pigmented skin lesions including the malignant form, that is melanoma. When a nevus is noted, those changes that are significant are related to enlargement , peripheral inflammatory changes suggesting mutations with a local immune response and ulceration again suggesting host immune response to destroy the lesion. If suspicious excision employed.

Nevus=cancer?: No one can be sure. So the preventative method is to biopsy the nevus.

Get your surgery: I don't know exactly what you have; perhaps the term "nevus" is mispronounced, but a suspicious lesion needs to come off. Get a consult with a dermatologist if you're in doubt.