After you've sent out your email campaign, you can view how well it's doing by going back into the campaign again.
In the Campaign, you'll be able to see:
The email sent from the campaign.
The average open percentage rate of the campaign.
The average click percentage rate of the campaign (if there's a clickable link in the email).
When it was created and when it went live.
How many emails were in the campaign.
How many recipients were in the campaign.
The exact number of opens and clicks.
The number of unsubscribes from the campaign and global unsubscribed emails.
You can also see exactly how each email is doing by scrolling down and clicking the Email or Email Messages section (depending on whether it's a bulk email or drip campaign) and clicking on the stats.
Finally, you can go into the Email Lists section and see the stats on each individual email address. Click the blue "Timeline" button to see what they did and when they did it.