On the average, women speak 21,000 words a day. Men only 7,000. Women are more relationship oriented than men. One way to build a relationship is to talk with a person. Men are not so relationship oriented. Sure, there are exceptions, but these are the averages.
I don't know you, so I don't know why you don't speak much. Maybe you are secure in yourself and don't feel a need to "prove" yourself to someone. Maybe you don't feel good about yourself, and don't want others to get to know you. The reasons can be endless.
When someone may ask me why I am so quiet I say, "Better someone to think I am a fool, than for me to open my mouth and erase all doubt"