Your cumulative ACT score is out of a total of 36 points. Each section (English, Math, Reading, and Science) is also scored out of 36. The average of your section scores gives you the composite value and is considered your overall ACT score. 

An average of 30.5 is rounded up to 31. Otherwise, scores round to the closest value. 

The essay is scored out of 6 by two separate graders. These scores are added up to give you your final essay score which is out of 12 points

A majority of schools only look at the cumulative score and do not look at your essay score at all. Schools that look at the essay will evaluate your cumulative score and essay score separately when considering you for admission. 

The ACT will provide a second grammar score that incorporates your essay score, but this combined score is generally overlooked.