| あのう → it has the same meaning as when you say um
| そうですか → the words can mean the same thing, but how you say it, you can change how the words are perceived; Rising intonation, "is that so?". or with falling intonation, "i see...". but both kind of mean that you under stand whatever was said to you.
| せんせい → is an honorable term used to describe someone else's occupation' "さくらはせんせいです" = "Sakura is a teacher"
| さん → is a general title placed on other people's names as a pretty respecfull term, but theres other things you can call someone to show more respect. this title goes after a persons name, first or last; さくらさん、さとうさん、海月さん
| when referring to someone... → あなた, or "you", is not commonly used in japan, (nor are pronouns like, he, she, or they.) instead, people just call you by your name and title like, 海月せんぱい or jellyfish senpai.