What would you do if you hear two people fighting in your building?

From where I stand, If I have met such a bad situation, I will try to take actions to clear the matter up. You see, If you don't know what have happened, you'd better not fall in hand to such things. As you have said above, both your boyfriend and you don't understand the language, so what should you do at first is to find whether their quarrel has some relationship with you or if the situation is becoming out of control, youd'd better call the police. Sometimes, to leave them some space to let them solve the problems is a better way.

I will try to understand matter first if I am unable to know their language will try to understand their expressions and what they are doing up to in case fighting leads to big attack also. I will keep eye on that matter and if I will find suspicious nature or any action that can lead to someone's life loss will try to call police or maximum group of people so that matter can sort out.

Personally I would stay out of it. Everyone is guilty of being passionate about something and fights are a fact of life. You wouldn't want the police called on you if you were having a disagreement with someone. The only way I would call the police is if someone is hurt or if they are being destructive. But I do understand that all the commotion can be extremely annoying.