Shopify supports variants such as sizes and colors, allowing you to manage the items as a group. People buying on your Shopify store will be able to select which variant they want from a drop-down. You can also create variants in Brightpearl either manually or by downloading them from Shopify. As long as each variant has the same SKU in both Shopify and Brightpearl inventory and orders will work fine.
Each variant in Shopify and in Brightpearl has their own separate product record, and so they connect as usual by SKU. Each item has its own inventory level managed by Brightpearl as for any other single product.
Variants can be created in Brightpearl as part of the product import from Shopify, options or option values will be created as part of the process. Where options and option values already exist in Brightpearl they will be re-used.
Note that Shopify allows a maximum of 3 dimensions for a product, for example, a product might have a choice of size, color and material. Brightpearl can support up to 4 dimensions for a product.