[PeterisP]

One definition of "understand" would be "have or obtain an internal model of Thing-or-process-to-be-understood which is close enough to reality that it allows you to reasonably predict what will happen and make effective decisions regarding that thing". It does not have to be a perfect model - if it would, then I'll be the first to say that I don't understand anything according to that definition, but it's a bit more tricky than it sounds on the surface. For example, for a self-driving car, "understanding pedestrians" according to this definition does require an ability to predict how they will behave and thus "know" what factors affect that - that the likelihood of a kid suddenly springing towards the middle of the road is highly dependent on the presence of a ball or a pet in that direction; that certain wobbly and jagged movements are indicators that the person might behave in a less predictable manner than the average person, etc, etc; and if a system does have this practical knowledge (measured by how well it is able to effectively apply it for its goals) then I'd say that it does have some understanding.