The Galaxy S7's touchwiz UI includes huge icons and large UI elements. You just can't fit much on this huge screen. On your homescreen you'd be lucky to get a widget and 8 app icons to fit. With DPI scaling you can make UI features smaller which means you can fit much more on your screen.
This feature is built into Android N. With Android N you can change your DPI on the fly. The feature is included in Touchwiz on the S7, but the setting to turn it on is hidden. You can access it in Nova Launcher via the "activities" widget. Start the "DisplayScalingActivity" activity. This launches a window giving you options to display standard or condensed. The condensed view will give you more space on your homescreen.
via XDA