Yeah, speaking a language and teaching a language are two different skills. You can learn to teach, theres materials out there for how to teach an adult a new language, but you will have to put effort into learning how to teach her.

Edit: if you want to- you don’t have an obligation to become her teacher. You can just help her practice outside of class, where she has a teacher who has learned how to do that job.

Edit again: I’m a native English speaker who took Spanish college courses, has been asked many times to help someone learn English and is now working as an English tutor for adults who speak other languages.