When you slide off the belly band (the green strip around the middle with the Panda bear on it) and open the card slowly...
In this case its another panda bear wearing a party hat with Happy Birthday in the background behind him. Once the card is fully open you can see the picture...
Watch my video below to see the shutter on the inside of the card in action.
Cardstock: Lemon Lime Twist, Whisper White, Basic Black
Paper: Petal Passion Designer Series Paper
Stamps: Party Pandas (Sale-A-Bration)
Ink: Lemon Lime Twist, Memento Tuxedo Black, Lemon Lime Twist & Pacific Point Stampin' Write Markers
Other: Layering Ovals & Circles Thinlits Dies, Stampin' Dimensionals, Sponge