You can restore it from the App Store. See instructions below from: Remove built-in Apple apps from the Home screen on your iOS device with iOS 10 - Apple Support
Restore a built-in app that you removed
- Go to the App Store.
- Search for the app. Make sure that you use the exact name of the app. Find the correct name of built-in apps.
- Tap to restore the app.
- Wait for the app to restore, then open it from your Home screen.