Condensed mode on Galaxy S7 (Edge) means more stuff to see on the screen by scaling down the icons, texts and some other graphic materials. To enable condensed mode on Galaxy S7, do as follows:
1. Open the Settings app on your S7
2. Go to the Display settings
3. Tap the Display Scaling option (It's right under the Font option)
4. There are 2 options here: Standard, Condensed
5. Select the Condensed mode and hit the Done icon
6. Now, you should feel the difference, as more content can be seen at a time on your Galaxy S7's screen
Note that, according to several reports, this feature has not yet been rolled out everywhere. For those who don't see the Display Scaling settings under the Display settings, can download the Nova Launcher and scale down the screen.