Your Will may be challenged if in the terms of the will adequate provision is not made from the estate for the proper maintenance and support of the your spouse, child or dependant, the court may, in its discretion, on application by or on behalf of your spouse, child or dependant, order that such provision as the court thinks fit shall be made out of the your estate for the spouse, child or dependant.

In other words if the court does not think you have left enough money to your dependents (spouse or kids) they may order your executors to give them more.