وَاعْلَمْ: أَنَّ الْمَرْفُوعَ الْمُتَّصِلَ خَاصَّةً يَكُونُ مُسْتَتِرًا فِي الْمَاضِي لِلْغَائِبِ وَالْغَائِبَةِ، كَـ «ضَرَبَ» أَيْ هُوَ، وَ«ضَرَبَتْ» أَيْ هِيَ.
Translation: Know that the nominative attached pronoun can be concealed in third-person masculine and feminine past-tense forms: ḍaraba contains an understood “he”; ḍarabat contains an understood “she”.
The book identifies forms where the nominative attached pronoun is concealed. The verb form supplies the subject without a separate visible noun or suffix.