What does Merged Version mean?

I see Merged Version at the end of my email subject line when I am TESTING my email personalization. What does it mean?

We recommend that you test your emails before sending them out to verify that they look and work the way you expect. The subject line of your test email will include the phrase "Merged Version". This will not be included in the final version of the email to your users.

If you have used merge fields in your email, the merge field will not display in the test email. The relevant merge field content will display once you send your email to your contact list.