The burner is what mixes the wick vapors, with the air, for combustion. A burner will have a lot of holes in it to allow air to pass through. The size of the holes is carefully calculated to give a clean burn. These holes should be kept clean. Sometimes carbon can actually block the holes and interrupt the clean combustion process. If this occurs, use a toothbrush to clean the burners.
Some people like to improve their appliance and so they tamper with the holes to allow more air to come in. This is not safe. You can possibly increase the carbon monoxide exposure. For sure, the combustion will change and, while the flame level may go up, the rest of the components will be harmed. If the burner is deformed, or the outer part is cracked or bent, the kerosene stove or heater should not be used.
The main thing to remember about the fuel burner is to keep it clean by using a toothbrush.