Reheating food to a high enough temperature can and does kill bacteria that can cause food borne illness.
Bacteria such as Salmonella that can cause salmonella poisoning is killed in the food when you cook and heat the food up to a high enough temperature.
You need to get the food to at least 165 F or above to kill the bacteria.
However if the food is actually spoiled then you should throw it out even though cooking it to a high enough temperature will usually kill that bacteria.
The food will be gross and not good to eat and still could make you sick.
But as long as the food is good to eat but potentially has some bacteria in it then heating the food up to a hot enough temperature will kill the bacteria.