Workouts enables you to track your workout progress by date or grouped by week/month/year to make it easier to see your progress over time.
It also offers a more visual way of displaying your workouts to further simplify comparing your weekly/monthly/yearly progress.
You can track workouts by using any of the health & fitness apps from the App Store or by using your Apple Watch Workout app.
You can also filter workouts by workout type and pick your favourite unit type.
The app shows all workouts from your Health/Activity app.