What is your relationship to your mom? The way you describe it, it sounds like she is putting you down which is sad and not ok. Shouldn’t she help you learn if she feels you don’t know? What is the point of giving you one day to prove yourself? But maybe there is context I am missing.

As others have said, you develop your ability to cook through repeated use, trial and error, and ideally knowledge passed down from your family. If you want to become someone who can cook, it won’t happen after one try or ten. Just keep trying out recipes that sound good to you, and treat each one as a learning experience. Overtime you will build up recipes that you have memorized and can riff on confidently.

You must like to cook, since you want to prove you can. Whatever you make, take your time, trust your gut, and do it to feed yourself something you like. Cooking is a personal thing, just because not everyone likes what you make doesn’t mean you can’t do it.