Hi and thanks for using the forum.
A red blood cell count is usually done as part of a CBC- complete blood count. 5.19 is within the normal range for red blood cells.
MCV is a measurement of the size of the red blood cells. Your result 77.3 is a little below the normal range.
MCH is a measurement of the amount of hemogolobin in the red blood cells. Hemoglobin is a protein found in red blood cells that carries oxygen. Again, your result is a little below the normal range.
Below normal values for these tests can indicate anemia. Your values are only slightly below normal so unless otherwise indicated by your doctor, I would not be too worried.