The model results consist of 5 tabs: New vs Returning, Retention %, Revenue New vs Returning, Number of orders New vs Returning, and Detail Tab (in case you are not familiar with the basics of the model, take a look at this link).
Depending on the aggregation level, you can see the number of distinct and returning customers detected in the time period on the New vs Returning Tab. For example, in December 2020, there were a total of 2.88k customers, of which 1.84K were new and 1.05K returning.
If you are interested in retention, the percentage of your returning customers, through a time period, switch to the Retention % Tab. The results in the Revenue New vs Returning Tab depend on the Model Scenario: if you have selected a monetary variable in the Model Scenario, you can observe her behavior, depending on the new and returning customers.
In the model scenario, you had to select the Order ID variable. That part was necessary so that you can track the number of orders over time for your customers in the Number of orders New vs Returning Tab. For example, we can see that returning customers are consistent throughout the period, i.e., they have a larger number of orders each month than new customers. Last but not least, on the Detail Tab, you can find a detailed table where you can see all relevant values which were used for the above results.