Here, you can specify how long you want the confirmation email to be valid (if you are using this option), and if you want the user's submission to be eventually destroyed.
This feature allows you to send an email to a specified address. For example you can send an email to the form's author at each new submission. This email can optionally contain the values submitted by the user.
If a user submits a form, they will receive an email with a confirmation link. Their submission won't be appear in the results until they have clicked on this link. This can be very useful if you want to make sure all submitted emails are valid.
Here, you can define conditions to validate a user's submission. If these conditions are not fulfilled, the submission won't be saved, and the user will be asked to modify their submission.
The less good part : if you mess around and end up breaking your form, don't come whining ! (Don't worry, you'll 'only' have broken your own form, the worst that can happen is having to start over a new one :)