COPY LOCATION CONSTRAINT
For this constraint to work we need two objects - a source(owner) object and the target object. Copy location constraint is applied on the owner object and the target object is the controlling object.
1.Once the copy constraint is applied on the source object, it copies the location of the target object. The source object will get located at the target object location.
2. Depending on whether X,Y or Z is ticked(selected), the corresponding X,Y or Z location of the target is picked by the source.If only X is ticked, the source will take the X value of the target. Either X, X and Y or X,Y and Z can be selected or its inverted values.
3. Activating the invert option will pick the negative value of the corresponding axis of the target object.