The Draft objects, and most Arch objects too, obey to a Draft system called working planes. This system defines a 2D plane where next operations will take place. If you don't specify any, that working plane adapts itself to the current view. This is why we switched to frontal view, and you see that we indicated a movement in X of 0 and in Y of 2.6. We could also have forced the working plane to stay on the ground, by using the Draft SelectPlane tool. Then, we would have entered a movement of X of 0, Y of 0 and Z of 2.6.