Chefs prepare food using a variety of cooking methods. In large kitchens they normally work as part of a team. The head chef runs the entire kitchen.
You may not need any academic qualifications to start work as a trainee chef. However some employers will prefer you to have a good general standard of education including GCSEs in subjects like English and maths.
To become a chef, you will need to have a keen interest in food and cooking, and be able to do several tasks at once. You'll also need creativity and imagination for food presentation.