After you've sent out an email from Email Manager, you can get statistics on the Date Sent, # Sent, Unique Clicks, % Clicked, and % Unsubscribes right on the Promote --> Email Manager screen. It's important to note that these numbers update nightly.
You can also drill into your individual recipients by clicking on "More" in the right column and clicking "View Recipients." There you can see who unsubscribed from your email, who clicked on it, and how many times they clicked. You can also go right into the individual recipient's Lead record from that screen. Check out help.hubspot.com for more on Email Manager.