A CBC measures the cells in your blood - red cells, white cells, and platelets. The most important number is Haemoglobin. Low Hb means your body isn't carrying enough oxygen, which causes fatigue and breathlessness. MCV tells you why - small cells point to iron deficiency, large cells point to B12 or folate deficiency. White blood cells rise during any infection or stress. Platelets handle clotting - a count below 1 lakh needs attention. No single number tells the whole story. Always read your results alongside your symptoms and discuss with your doctor.