How do I handle it when they bully my friends and I am too afraid to help him/her?

I would start by putting myself in my friends shoes. How would I feel if I were being bullied and my friend was too afraid to help? I would 100% help if I had the ability to, because I would want my friends to help me. No one ever wants to feel like an outcast or excluded, so it's important to always helped your friends and loved ones; even if that means going outside of your comfort zone. Friends and family are everything, you want them to know that you will always be there for them and that they can count on you.