CAMHS is short for Children and Adolescents Mental Health Service.
It's a team of different experts like doctors, therapists, and social workers, who will help you if you are feeling sad, anxious or having trouble at school they can help
Usually, someone, like a doctor or teacher, refers you to CAMHS. They work closely with you and your family to understand what you are going through. They can offer different services, like talking to someone, therapy, and sometimes medicine.
CAMHS can be in a clinic or hospital, but they can also meet you in a place like a park or café if it's easier for you. They see you regularly. If you're unsure, it's good to ask your doctor or another adult for help.
You can find out more information here