[And if We delay the punishment from them to a numbered term] means: to a counted time.
﴿وَلَئِنْ أَخَّرْنَا عَنْهُمُ الْعَذَابَ إِلَى أمة مَعْدُودَة﴾ أَيْ: إِلَى حينٍ مَعْدُودٍ.