Sholat together (congregation) is some men do sholat with a bunch of the Muslims in the mosque. The sholat in congregation that shohih and reinforced by Al-Qur'an and As-Sunnah is mandatory.
Alloh SWT said :
"And bow (in sholat) with the people who are bowed".
Al-Baqarah : 43
And Prophet Muhammad SAW said:
" For Dzat that my soul is at hand. I mean, I'm actually trying to order (Muslims) to collect firewood, and tied. Then I hereby order that sholat in congregation was founded, so that the summons to prayer was on the air. After that, I'm going to tell someone to lead the Muslims. Furthermore, I will visit the man who didn't go through prayer in congregation, then I burned all their home".
Ibnu Majah (793)
And then can womens attending sholat in congregation at the mosque?
Prophet SAW said :
" Don't you ban the women who get to the (perform a sholat) in the mosque, but in their home. It's better for them".
Muslim (635)