Joins is a feature which allows the user to join the fact table (from which the model is created) with other models. All the dimensions present in the joined Model can be used in this model. For example, an Order Model having customerId as one of the columns can be joined to the Customer table. Similarly it can also be joined to the Product table.
In Model joins, the Joins type can be selected from a list, say, Left Outer, Right Outer, Inner, Full Outer Join. In addition to that, multiple conditions can also be created at one instance to join two models.