الرِّجَالُ قَامَتْ — The men stood. الرِّجَالُ is the mubtadaʾ; the subject of قَامَتْ is the concealed pronoun «هِيَ», and the verbal clause is the predicate.
In الرِّجَالُ قَامُوا, «الرجال» is the mubtadaʾ; «قاموا» is the past verb, wāw al-jamāʿa is its subject, and the verbal clause is the predicate. The book permits both structures.