Unregulated mods are also known as mechanical mods or mech mods. Mech mods are a type of e-cigarette device which will ordinarily* provide direct, unregulated power straight from the battery or batteries. There are a variety of different configurations available ranging from very simple tube mods which take a single 18650 (or 18350, or 26650, etc) up to series mech mods and parallel mech mods which can take two batteries and either double the voltage, or effectively double the mAh capacity to give longer battery life respectively.
If you’re new to vaping, you should steer clear of mechanical mods until you have a solid understanding of the risks of using them, or rather misusing them, before buying one. They’re not inherently dangerous by any means, but in the wrong hands they definitely can be, do your research and make sure you always treat them with respect no matter what your level of experience.