In English-language newspapers, especially in the United States and Britain, a pol is a politician. It is a clipped, slightly knowing office word: the kind of thing you meet in a headline or a political column, not in a school essay and not when you introduce someone politely. A pol may be a mayor, a member of parliament, a party operator — anyone whose job is politics. The word itself is not a heavy insult, though actually the sentence around it often is; it treats politicians as a type, the way cop treats police. Students almost never need to say this. They only need to recognise it when a paper uses it.