The "banana braid" is a style of braid where strands of hair are braided along the length of the head, usually starting at the nape of the neck and moving up towards the crown of the head, creating a shape similar to that of a banana .
"D-4" could be an internal code or manufacturer-specific designation for this style of banana braid. The ":1/12" may indicate a specific size, perhaps a smaller size or a particular variation in braid style.
Without more context, it is difficult to give a precise interpretation of this mention. If you require more detailed information about this product or designation, I recommend consulting the details provided by the manufacturer or seller for further clarification.