Assuming you are referring to the functions of a standard car vacuum cleaner:
Most car vacuum cleaners will have a crevice tool to help you reach tight spaces, a brush attachment to help clean upholstery, and a long hose to help clean hard-to-reach areas. Some higher-end models may also have a LED light to help you see under the seats.
The purpose of a car vacuum cleaner is to help remove dirt, dust, and debris from your car’s interior. This can help improve the air quality in your car, and make it easier to keep your car clean.