First, let's explore the definition of torque. In Physics, torque refers to the rotational equivalence of the linear force. In other words, it's a linear force applied from a certain distance from the rotation axis and the vector of the force is perpendicular to this distance. It's important to know that the larger is this distance, the greatest the torque would be, which is the reason why a wheelbarrow helps to transport heavy objects.
Specifically, if you try to lift a heavy object just with your hands, you would require a greater force, than when you use a wheelbarrow because this tool allows you to increase the force you use. Using a wheelbarrow your force will be transformed in torque because of the distance from the point where you applied the force and the pivot point at the wheel, allowing you to lift a heavyweight with less force.