This is the 4140th most frequent Arabic word.
شاحنات
Trucks.
In this sentence, 'الشاحنات' (trucks) is used as the subject performing the action of crossing borders.
تمر الشاحنات الكبيرة بالبضائع عبر الحدود يوميًا.
The large trucks carrying goods cross the borders daily.
Here, 'الشاحنة' (truck) is a singular form used to describe the vehicle delivering parcels.
وقفت الشاحنة أمام البيت لتسليم الطرود.
The truck stopped in front of the house to deliver parcels.
In this case, 'الشاحنات' (trucks) is again the subject, emphasized by the specific nature of the vehicles ('heavy').