Negative work simply means our object loses energy, while positive work means our object gains energy. Now, whenever a nonfictional force is applied, work can be found using the following equation work is equal to the force applied on our object, times the distance our object moves. And since work is, in fact a scalar, a vector times a vector gives us a dot product. So that means we take the cosine of the angle. If you want to learn more about dot product and cross product, check out the lecture on that. So, basically, if we have some object, say, this block, and we apply a force with an angle theta to the horizontal of that object, and our object moves a distance d we can find the amount of work done on the object.