It tracks your steps, heartrate, stairs, provides the weather and shows your texts and allows you to control music (for me Torah Anytime shiurim) on your phone.
But even more, it has a built in GPS. For the last five or so years I have gone bicycle riding for exercise, almost 12 months a year. The watch works with an app on your phone to show details for the ride including average MPH, elevation, calories burned, heart rate for each segment of your ride. The app will also show a street map or satellite map which correlates these activities.
Here is a review -
https://www.techradar.com/reviews/garmin-vivoactive-3-reviewPM me with any other Qs.