Absolute values are used for determining the magnitude of a number, so they are often used for distance measurements. They are also sometimes used for financial transactions. Absolute values are used when negative values are not possible.
No matter what direction it is moving, a car is also moving in a positive direction; it can never move at a negative speed. However, when a car is traveling toward a particular destination, its velocity toward it can be negative. Because of this, a car's speed is equal to the absolute value of its velocity if it is traveling directly to or away from the target.
This is because velocity is a vector value, and speed is a scalar value. Scalar units measure the overall speed of an object, which must be positive. Vector units measure speed and direction, so they can be negative.
Absolute values are also useful in some financial scenarios. The money involved in a transaction, for example, is always positive, so the absolute value can help people determine the total amount of money that moved. Stock exchanges and other financial entities are often analyzed, in part, by how much money is moved in a particular period of time, and absolute values are needed to calculate this amount.