A bundle is when you have a listing that carries multiple products, where each product is also being sold separately as single products.
Let's take an example that you have an Amazon listing that sells a kit consisting of 3 products, a Phone, a Wall Charger, and a Car Charger. Then, you have separate listings that carry just a phone, and so on.
To handle it in Planyard, you would create 3 separate products accordingly. Then you would map all 4 listings to their respective product/s. The bundle will be mapped to 3 products, and the singles will be mapped to their respective product.
Please note, that in Planyard, every SKU needs to be mapped to a product. A single item would be mapped to a single product. A SKU carrying multiple products, would be mapped to all respective products.
Mapping is done best in Inventory>SKUs>Show Sidebar per below: