I = Ben 

You= Sen/Siz

* In English for plural and singular person is expressed by the same noun ´´you´´ , but In Turkish , Sen is ´´you´´ for only one person , Siz is for the plural ´´you´´ -  when you want to address more than one person , again Siz is used for  the expressions that includes respect , it could be someone  elder than you , someone who has a higher position than you (like a boss ) , or someone you just don´t know about , or the person you have just met , you want to keep the distance and be respectful  as we start to open up after a while passes to get to know each other , not directly BOOM you know :D

They : Onlar 

He/She/It = O 

* Yes this easy you can use  ´´O´´ for  all of these 3 categories . Turkish isnt a sexual language

But if you want to point out the person you are talking about is a girl , maybe you want to make your girlfriend jealous , in this case say ; I like this girl , she is awesome ---> Bu kızdan hoşlanıyorum .O harika. (again here when we said she we said O regardless to gender . But this time we specified the gender by just saying ´´the girl´´  --> Kız

We = Biz