This refers to the product of blending various types of coffee, usually performed by the roaster to create a product with a certain aromatic profile and characterised by a certain degree of consistency over time.

There are two main methods for producing a blend: pre-blending, where the roaster blends various types of coffee prior to the roasting process, and post-blending, where the roaster blends various types of coffee after roasting.
The second method is definitely the better option, as the various types of coffee are roasted separately, each according to its own “recipe”, developed to best allow its features to stand out, and then blended.