It means you may have a higher risk of an infection or you can get sick easily.
What Can Happen If I Have Low White Blood Cells?
It means you immune system is very low and you are at risk of picking up any bug.
If you have a low WBC (white blood cell count) and you are not sick or have an infection, it may just be your normal level wbc. If you are sick it means you have an auto immune difficiency, like HIV AIDS.