The term Fireman now almost invariably refers to a Firefighter.
In the 19th century and early 20th century "Fireman" was also the designation for someone whose job it was to tend a fire, usually for running a steam engine. Steam locomotives, saw mills, etc would employ "Firemen". Often much of the job was hard physical labor, such as shoveling coal into the engine's burner.
Steam locomotive firemen were also usually responsible for cleaning the ash and dust from the burner prior to lighting the fire, adding water to the engine's boiler, making sure the a proper supply of fuel for the engine is on board before starting journeys, starting the fire, raising or banking the fire as appropriate for the amount of power needed along particular parts of the route, and performing other tasks for maintaing the locomotive according to the orders of the locomotive enineer. Some firemen served these duties as a form of apprenticeship, aspiring to be locomotive engineers themselves.