Ruleset Mappings summarize how well a given ruleset applies to the dataset, and to what extent the masking job will be successful in masking what is at risk.
The mappings start by breaking down the total number of fields and tables that have or have not been categorized as sensitive. Some fields will simply have no sensitivity value, and as such, should be checked. So if the % of fields or tables that have not been categorized is high, it is recommended going back to edit a ruleset. From those fields that have been mapped as sensitive, some might have an algorithm, while others might not have a mapped algorithm. If a field is flagged as sensitive but has no mapping to an algorithm, a user should take action to ensure those fields are being properly masked.