Build filters to ensure your modifications are only applied to products that match your criteria. By not creating a filter, you are enabling a rule to apply to ALL PRODUCTS in your feed. Filters can consist of single attribute criteria or multi-attribute criteria by clicking Add Filter to build each additional criteria desired.
AND vs OR Filters
Filters can differ by their function using AND / OR logic. To create an OR logic, a filter must have multiple values entered at once:
To create AND logic, there must be multiple filters that all determine the select criteria: