Whether the demand in the panels satisfies the weak axiom
So WARP says that if bundle x' you choose under budget B' is affordable at budget B'' (and you don't choose x' - i.e x'$\not=$x''), then x'' cannot be affordable under budget B'.

The picture you showed gives the 2 bundles that the person chooses. Those are given in the picture. As you can see, x' is not affordable at budget B'' and bundle x'' is not affordable at budget B', so WARP is satisfied. 

If you are reading MWG and you don't understand what those dots represent in the consumption space, then I would recommend reading more from the beginning of chapter 2.