The number entered here determines how many items will be used in the assessments. Depending on the type of grading strategy, this number gives the number of comments, assessments elements, bands, criteria or categories (sets) of criteria in a rubric. Typically an assignment will have something between 5 to 15 assessment items, the actual number depending on the size and complexity of the assignment.
All assessments have a General Comments field. For a "No Grading" assignment the value given here determines the number of additional comment areas. It can be specified as zero and results in the assessment having only a single General Comments area.