two-wheel drive is the only two of the four wheels are powered by the transmission. In a rear-drive car, the back wheels are powered and the front merely steer. In a front-drive car, the forward wheels are powered and steer, leaving the rear wheels to follow along.
Two-wheel drive, also known as 2WD, refers to a drivetrain configuration in vehicles where power is delivered to only two wheels, usually the front or rear wheels. This differs from four-wheel drive (4WD) or all-wheel drive (AWD) where power is delivered to all four wheels.
It is more likely that you're referring to "two-wheel drive" within the context of Automotive engineering, where it is commonly used for cars, trucks, and other vehicles. In this context, a two-wheel drive vehicle only powers either the front or rear wheels, and this can affect the vehicle's performance in certain driving conditions, such as on slippery or uneven surfaces.
Examples of vehicles that might use two-wheel drive include most sedans, coupes, and hatchbacks, some pick-up trucks, vans and sport utility vehicles (SUV) and also bikes, motorcycles, etc.