PLEASE HELP ME I DONT UNDERSTAND THE adjective clause PLEAS HELP

1. The picnic that we planned was canceled.

2. This picture that you gave me is beautiful.

3. Each student who reads five books will get a prize.

4. Benjamin Franklin was an inventor who astonished his friends.

5. My aunt is a character who you won't forget!

6. The hikers who completed the trail were tired.

7. Suzy's dress that her aunt sewed was beautiful.

8. Their game that was so important was forfeited.

9. That book, which was a best-seller, was dull.

10. Those dishes that he gave me chipped easily.
AND PLEASE NUMBER IT