Rubrics are an advanced grading method used for criteria-based assessment. The rubric consists of a set of criteria plotted against levels of achievement. A numeric grade is assigned to each level. For each criterion, the assessor chooses the level they judge the work to have reached. The raw rubric score is calculated as a sum of all criteria grades. The final grade is calculated by comparing the actual score with the worst/best possible score that could be received.

The details of Rubrics settings could be found here: Moodle – Rubrics Guide