恥ずかしがり屋って英語でなんて言うの？

In American English, we usually use the word 'shy' to people speak very little and take a submissive posture in social situations. This shy behavior stems from a fear of social judgement or evaluation. This is to be contrasted with 'introvert', which simply means that one's life energy tends to flow inward (toward ideas and silence) rather than outward toward people and things, and has nothing to do with fear of social evaluation. I hope that this is useful to you in your studies.

Shy people normally do not like the attention of any kind. When going to parties, they will sit or stand alone and they try to not draw any attention to themselves. You can use the following expressions: "He's a very bashful person!" "She is a very reserved person!" "bashful", "reserved", "introvert" are synonyms of shy "She is a wallflower!" This is an English expression to describe a shy person.

A person who is quiet or nervous and doesn't like to be around people is referred to as a 'shy person' the term used for this is an 'introvert' Timid also means the same as shy and they don't have much courage or confidence

"Anti social" is often the word used to describe someone who isn't very good in social situations/around a group of people. "Introvert" also used to describe someone who is shy, "Extrovert" is the opposite to this, someone who is very comfortable in social situations.

Somebody who is shy is known as a "shy person". You could also call them an "introvert".