Complex sentence: If you were only half way through this WBS component, then the PV would only be $500 because you are only half way through completing this task, so you only planned on spending half of the budget at this point.
Split into simpler sentences: If you were only half way through this WBS component, then the PV would only be $500 because you are only half way through completing this task. In simpler terms, you planned on only spending half of the budget at this point.