What is my girlfriend has bruises on her body?

As an AI language model, I am not capable of knowing your girlfriend's personal and medical information as well as the circumstances behind her bruises, or whether or not they should be concerning. In general, bruises are caused by minor injuries to the skin that cause bleeding under the skin's surface, and they often heal on their own after a few days or weeks. However, if the bruises are severe or appear without any known cause, it is recommended to seek medical attention. It is important to communicate with your girlfriend and ask her if she needs any medical assistance, support or if there is anything else she needs from you. If you suspect domestic violence or abuse, do not hesitate to seek help from authorities.