All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
There is no doubt that learning Arabic with a female teacher and with women is better than learning it with a group of men. However, if there is no course for women, there is no harm in learning with a group of men on the condition of observing the Islaamic requirements, like wearing Hijab, not wearing perfume when going out, not speaking in a soft voice, not being in seclusion with one of them, and not sitting beside one of them, but rather sitting in the back (behind men). So if all of these conditions are met, it becomes permissible for you to attend this course with them, otherwise it is not. There is no doubt also that if a group of women were present with you it would be better, so you have to try to convince other sisters to attend this course while observing the above requirements as well.
Allaah knows best.