What does Cherry mean when she says Bob “wasn’t just any boy"?

Bob was her boyfirend..... he wasn't just any boy in her eyes. He was a very special boy. 

To Cherry, Bob was not just a violent Soc who enjoyed fighting Greasers and getting drunk. Cherry understood that Bob had two different sides to his personality and tells Ponyboy that Bob was actually a sweet, friendly individual. He was Cherry's boyfriend, a special to him.