In the upper right corner, you'll see Track ## Results. Tracking is a way to keep track of your properties or people. After you track properties, in the Remine desktop application, you'll get notifications on changes to your tracked opportunities on the Engage page.
If you tap this button, you'll track the properties. They'll automatically be added to a label indicating the date and that they're properties you tracked from the mobile app. You can see the labels and manage them on the Track tab.