Well, theoritically, if you put أستاذةُ in the construct state (by ending it in -u instead of -un, or if you're ignoring the case endings, by simply pronouncing the ـة as an -it instead of an -ah), and put عربيةٍ in the genitive (by ending it in -in instead of -un), you'd be saying "Samia is a professor of Arabic." But while that would make perfect sense in dialect, in MSA, it sounds weird to refer to the language using the indefinite, and it also sounds weird to refer to it using the definite, because then you'd be saying "Samia is the professor of Arabic," so I'm actually not sure how to best phrase it in MSA. This course teaches you an amalgam of MSA and dialect anyway, so I'd say just go ahead and say:
ساميةُ أستاذةُ عربيةٍ saamiyatu 2ustaadhatu/2ustaadhit 3arabiyya(tin).
For the sake of comparison, this sentence as it currently stands is:
ساميةُ أستاذةٌ عربيةٌ saamiyatu 2ustaadhatun/2uustaadhah 3arabiyya(tun).
Hope this helps.
In English, a professor is someone with a doctorial degree who teachers at a college or university. A teacher is anyone who teaches you anything. It is the term used for people who teach students below college level. Where I'm from, teachers who have less than a doctorate who teach at colleges are called "instructors". In my Arabic/English dictionary, استذ is translated as "professor" and مدرس (mudarris) and معلم (mu3llim) are translated as "teacher". "Mu3llim" is also translated as "instructor".