My father has a sharp pain on the bottom left of his stomach and that pain is really sharp .what must i do or maybe yourll can tell me whats happining?

Pain is sharp: but it is severe. Sharp, severe abdominal pain warrants emergency evaluation.

Left lower quadrant: The anatomical area you are referring to is the left lower quadrant. If your father has 10/10 pain, I would bring him to the ER for evaluation, full history and physical exam. If he has fever, nausea/vomiting associated with this pain it could be diverticulitis. Other possibilities are constipation, bowel obstruction, kidney stone, and if is higher, peptic ulcer disease/cardiac disease. Seek care