My period is normally a darker red and brown color. but now it's a lighter red? what does this mean?

Nothing : it really has no significance. Nothing to worry about.

Vaginal bleeding: The darker blood is indicating that your uterus is probably shedding the uterine lining & the hormones are changing which is normal.

Nonspecific: Some menstrual periods can be heavy, light or irregular. If there is chance of pregnancy a home pregnancy test would be helpful. See your doctor for more answers.