What is the point of girls wearing Hijab?

I don't know about other girls, but I'm 14, and my friends and I wore hijab with jeans (not jeggings or skinnies), tops, full sleeved shirts underneath them or cardigans over them. We don't wear completely tight clothes, but we don't wear baggy clothes either. We wear clothes that don't show are figure, but don't hang over us like blankets.