contains / does not contain condition will allow you to utilize individual mapping strategies for individual items or item groups. You can assign a few values to items depending on what the value incorporates (or doesn't incorporate).
You can use this option to set the value Adidas, if the source's manufacturer or title attribute contains the value Adidas you can set the brand to Adidas. If it does not contain the value Adidas, Store Name will be set.
It is always recommended to have a Fallback rule for products that are not matched by the condition, just to make sure that there are no empty values in your output feed.