Used for: replacing multiple values in certain fields with other values. It can also be used for deleting a value (replace by nothing). Note that this rule is case sensitive by default!
With the "replace multiple values" rule you can look for a certain value in a particular field and replace it with another value of your choice. If you don't enter a replacement value, you replace the value you search for with nothing (=deleting the value). Also, if the value you want to replace is not found in the field you select, the rule will do nothing, so it will not randomly add the replacement value in that case.
You could, for example, use the "replace multiple values" rule to change color names. This example is shown in the screenshot below.
Besides searching for a value and then replacing it with another value, the "replace multiple values" rule can also be used to delete certain values from a field. In this case you just leave the "Use replacement" field empty. The screenshot below shows an example in which the sizes "small" and "large" are deleted from the title of every product.