Yes they are normal subjects, you have to do English (literature and language as two different GCSES), maths, science (some schools make you do it as biology, physics, chemistry separately or you can do it as combined) and then you choose the others you want to do these are based on what you’re good at or maybe want to do in the future
You can do a language, history/geography, business, media studies, a creative one textiles/food tech/art/graphics/drama/music etc some schools make you do more than others
Drama, business and textiles which she did are very normal and common subjects to do at GCSE
you also only NEED to pass maths and English if you fail you have to resist them which is what she’s doing if you fail the others it’s normally whatever unless you wanna go to a specific sixth form/college that requires you to get certain grades in certain subjects (or if you failed a subject you wanted to carry on doing at college you have to retake)
also if you plan on going to uni you might want to retake if you did badly because sometimes they look at GCSEs but they mainly look at a levels which are the next exams (I don’t think she’s doing them)
I did my GCSEs a few years ago before they changed but pretty sure that’s still right
Also she’s been on holiday all year and was on holiday in the break between exams which says it all, her parents clearly don’t care or they would’ve sacrificed one of their 10 holidays a year to let her study properly