why do my raw photos have a significant amount of grain?

Raw vs JPG.

I'm new to photography and am practicing editing photos.

I have been editing my jpgs as I haven't shot RAW+JPG till recently but as this is my first photo I decided to edit, I noticed it was super grainy. Is this normal or just a bad photo? Is there any specific trick to fixing it or do people go about it in different ways? Also, if I'm shooting in auto, is there any way I can avoid this in the future?