why girls are so shy

That goes for all girls. There are very very few girls who are not shy to start a conversation with a guy because in our society, it's usually the guys who start conversations. When a girl sees a guy she likes, normally she does nothing because she's too scared and shy to approach him. Usually she just sits there and hopes "I wish that cute guy will come over and talk to me!"

Guys are the ones who normally initiate conversations and ask girls out on dates. Girls are terrified of appearing "easy" or "slutty" if they make the first move, which is why they rarely do.

That's why anytime a girl starts a conversation with a guy, she's going to be super shy.

A while ago this girl who's my friend told me that there are a bunch of girls who want to be my friend but are to shy to say it.

For some girls, shyness is actually fear an excessive fear of new people and situations.  A shy girl assumes others are going to evaluate her negatively.  When Kelly’s father presents her to his friend, her adrenaline surges, her heart pounds and her stomach flutters.  While her body churns, her mind freezes.  She can’t remember the name of the woman she just met.

But what about the girl who is nearly always cautious around people? Perhaps she is highly sensitive and finds the world a little overwhelming.  Perhaps she was born with shyness as a part of her personality.  One of my own daughters is shy.  Her comfort zone, the times and places she feels completely at ease, is very narrow.  Does her shyness keep her from pursuing her dreams? That remains to be seen.  But the more I learn about shyness, the more encouraged I become.