Specifies in ad hoc analysis whether instances are counted in reports. Meaning, if you have multiple sequential values for the same variable you can count them either as one or multiple instances of the variable.
For example, you might see repeat page reloads, which are the number of times that pages on your website are reloaded or refreshed during a single visit. This option lets you specify whether multiple hits on the same page are counted as one, or as multiple page views.
The metric Single Page Visits is equivalent to both Single Access AND Bounces in Reports & Analytics, depending on whether Count Repeat Instances is set to Yes or No.
See Settings Tab - Descriptions in Ad Hoc Analysis Help.