The Response specifies what you're returning to the front-end or any service you're connected to. In the example below, you can see that after this API Endpoint executes, it's going to return the variablenewuser .
If we Hit Run & Debug, this is what the newuser variable might look like:
You'll notice in the response section that the return type is as self :
This simply means that it's going to return the newuser variable as it's own object without being labeled anything. You can change the return to anything you like as shown below:
If you want to add more variables from the function stack to your response, you can simply click the plus button to do so: