Polite language: a form of speech or writing that shows respect to the listener or reader. In Japanese, typical forms are the "-masu" and "-desu" endings.
面接では丁寧語を使うのが一般的だ。
It's common to use polite language in interviews.
「〜ます」「〜です」は日本語の代表的な丁寧語の形だ。
"-masu" and "-desu" are typical forms of polite language in Japanese.
友達には丁寧語を使わずため口で話すことが多い。
With friends people often don't use polite language and speak casually.
子どもに丁寧語を教えるときは、基本形からゆっくり説明するとよい。
When teaching children polite language, it's good to explain the basic forms slowly.