What is the definition or description of: red cell count?

The absolute number: Of rbcs per micorlitre. Not all that helpful clincially, so we use hemoglobin (HGB) and hematocrit (hct).

How many blood cells: An rbc count is a blood test that tells how many red blood cells (rbcs) you have. Rbcs contain hemoglobin, which carries oxygen. How much oxygen your body tissues get depends on how many rbcs you have and how well they work. http://www.nlm.nih.gov/medlineplus/ency/article/003644.htm.