Tracking is a way to keep an eye on a property. When you track an opportunity, it appears in your comprehensive list of opportunities on the Track tab in mobile. After you track a property, you'll receive notifications on the Track page in Remine Desktop when information associated with that opportunity changes.
In Remine, you can think of tracking putting your opportunities in a box. Labels are your filing system for everything that's inside the box.
See the How do I track properties or people? article for tracking instructions.