This is the 568th most frequent Spanish word.
carga
Load or burden.
In this sentence, 'carga' is used to denote the physical load or freight that the truck is carrying.
La carga del camión es muy pesada.
The truck's load is very heavy.
In this case, 'carga' refers to the electrical charge that the battery holds.
Asegúrate de que la batería tenga suficiente carga antes de salir.
Make sure the battery has enough charge before leaving.
Here, 'carga' metaphorically refers to the burden or weight of responsibilities.