I wrote about my country's culture in English. Would you check it?

Actually this is very good, There could be some phrasing changes to make the subjects agree. You are mostly speaking in the third person so you would not use the pronoun I in the same sentence that you have used a third person phrase. I am not sure I make myself clear either. I'm not an English treacher. In the sixth sentence I would say it like this. ...it is considered impolite for (a person to speak frankly) of what (they) want. It is OK to move from third to first person when you change paragraphs but awkward sounding in the same sentence or paragraph. Hope I helped you. Keep up your good work.