Erythrocyte indices are crucial measurements in a complete blood count that help in diagnosing and classifying types of anemia based on the size and hemoglobin content of red blood cells. These indices include Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), and Mean Corpuscular Hemoglobin Concentration (MCHC), which provide valuable insights into the underlying causes of hematological disorders.