My friend said that her vagina itches a little and smells like fish and when she wipes it has light pink blood her period is irregular do you know be?

Infection. Those are classic symptoms of a vaginal infection called "bv" or bacterial vaginosis. It is caused by an overgrowth of normal bacteria in the vagina. The treatment is a prescribed antibiotic. If she is sexually active it may also be a sexually transmitted disease. She needs an exam.
Vaginal odor may… Come from yeast overgrowth ("infection"), chlamydia infection, bacterial vaginosis (formerly called gardnerella infection), trichomonas infection, etc. Latter 3 r std's & need to b seen & treated by pcp/gyn. Yeast may respond to otc creams/suppositories or may require rx-strength antifungal. Make sure her partners r checked & treated, too; otherwise there's chance of re-infection.