Has your singing teacher referred to the Fach System? You didn't like to admit it was unfamiliar? It's the German way of categorising voice types.
Panic not! We have a book about it in the Whittaker Library:-
What the Fach?! The definitive guide for opera singers auditioning and working in Germany, Austria and Switzerland, by Philip Shepard. Catalogue details here.
You can also read a page about it on our IPA Source database - the database which gives the IPA pronunciations of opera and song texts. The Royal Conservatoire of Scotland has a subscription, which our staff and students can access online, on campus. Check it out here:-
Here's the page about the German Fach system. (You'll need to be on site to access it.)