Take it as an example what happened today. Mr. Smith thought that you're insulting him by saying Italian phrases. What you've done is an example of language barrier in communication. Language barrier is the difficulties in communication experienced by people or groups originally speaking different languages, or even dialects in some cases.
Mr. Nat, you know that we have a rule in our school that we should avoid using other languages to avoid breakdown in communication
Now Mr. Nat, please apologize to Mr. Smith.
Apology accepted Mr. Nat. Next time, you should be careful in communicating to avoid misunderstanding okay? You can go home now Mr. Nat.
I'm sorry Mr. Smith I won't do it again
You can go home now Mr. Nat. Always remember what we said to you.