To x-ray something is to take pictures of the inside of your body. Doctors x-ray patients all the time.
You've probably gotten x-rayed by a doctor, and maybe you saw the weird-looking pictures — x-rays — of what the inside of your chest, head, or leg looked like. Doctors x-ray patients to see if a bone is broken or look for serious conditions like cancer. Dentists will x-ray your mouth to get a better look at your teeth. When they x-ray you, you'll often wear some lead over part of your body, because the radiation in x-rays can be dangerous.