ضَرَبْتُ أَنَا وَزَيْدٌ
Translation: Zayd and I struck (someone).
Ḍarabtu: past-tense verb; the attached -tu is its subject.
Anā: separate pronoun emphasizing that attached subject.
Wāw: coordinator.
Zaydun: nominative coordinate of the attached subject pronoun.
Anā is reinforcement, not an additional independent agent.