وَالثَّانِي: مُسْنَدٌ بِهِ، وَيُسَمَّى الْخَبَرَ.
Translation: The second is the element through which something is predicated; it is called the khabar.
The khabar completes what is asserted about the topic. In «زَيْدٌ قَائِمٌ», «قَائِمٌ» tells us Zayd is standing. The relation between subject and predicate makes a complete statement.