Kinetic energy is either zero or positive, never negative. This is because kinetic energy is defined as half an objects' mass multiplied by the square of its velocity. Since mass is a measure of matter, it can never be negative, and since velocity is squared, it is always positive.
The kinetic energy of an object is the energy caused by an object's motion; if the object has any type of motion, it has a positive amount of kinetic energy. Unlike some other physics quantities, such as velocity, kinetic energy is not concerned with direction; it's only concerned with magnitude. Because of this, even if an object has "negative motion" by moving in a direction opposite to what's considered positive, the sign of the kinetic energy is unaffected.