It means, that you don't have video card, and game is using CPU to render images (which quite slow, because CPU already processing game logics, code of OS and all opened applications, and adding rendering of images is quite troublesome). Or, another option, you do have video card, yet drivers not installed or installed in a wrong way. If it is the case - find data about your video card (manufacture, model), go to site of manufacture (Nvidia or AMD, you don't have many options here really) and download drivers for your model of videocard. And install it.