When you send out an email and enable the top 2 settings:
Then the users who open the email or click on the links or orders through the link will be tracked.
This is great for tracking to see which emails do good, if it's the same users all the time, etc.
To view these statistics after the email has been sent, you need to click on Marketing > Statistics:
You'll then need to change the dropdown to 'email campaigns'
If you then scroll down, all your emails will appear there:
Then, if you click into that email, you'll see 'load more statistics', it will pull up the users who have clicked, opened, ordered, unsubscribed, etc.