apple watch

I guess you either swiped to change to a different watch face, or removed a complication. Both are easy to do while learning a new device.

Change your Apple Watch face - Apple Support

Try a hard restart on your Apple Watch. To force restart your Apple Watch, press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo. Sometimes just powering off for about 30 seconds and back on works as well.