قَائِمًا كَانَ زَيْدٌ
Translation: Zayd was standing (the predicate comes before the verb).
قَائِمًا: accusative khabar kāna fronted before the verb.
كَانَ: past incomplete verb.
زَيْدٌ: delayed nominative ism kāna.
Compare with «كَانَ زَيْدٌ قَائِمًا» and «كَانَ قَائِمًا زَيْدٌ»: the primary case relations stay intact across the three orders.